Aims. This study investigated vancomycin-microbubbles (Vm-MBs) and meropenem (Mp)-MBs with ultrasound-targeted microbubble destruction (UTMD) to disrupt biofilms and improve bactericidal efficiency, providing a new and promising strategy for the treatment of device-related infections (DRIs). Methods. A film hydration method was used to prepare Vm-MBs and Mp-MBs and examine their characterization. Biofilms of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli were treated with different groups. Biofilm biomass differences were determined by staining. Thickness and bacterial viability were observed with confocal laser scanning microscope (CLSM). Colony counts were determined by plate-counting. Scanning electron microscopy (SEM) observed bacterial morphology. Results. The Vm-MBs and Mp-MBs met the experimental requirements. The biofilm biomass in the Vm, Vm-MBs, UTMD, and Vm-MBs + UTMD groups was significantly lower than in the control group. MRSA and E. coli biofilms were most notably damaged in the Vm-MBs + UTMD group and Mp-MBs + UTMD group, respectively, with mean 21.55% (SD 0.08) and 19.73% (SD 1.25) remaining in the biofilm biomass. Vm-MBs + UTMD significantly reduced biofilm thickness and bacterial viability (p = 0.005 and p < 0.0001, respectively). Mp-MBs + UTMD could significantly decrease biofilm thickness and bacterial viability (allp < 0.001). Plate-counting method showed that the numbers of MRSA and E. coli bacterial colonies were significantly lower in the Vm-MBs + UTMD group and the Mp, Mp-MBs, UTMD, Mp-MBs + UTMD groups compared to the control group (p = 0.031). SEM showed that the morphology and structure of MRSA and E. coli were significantly damaged in the Vm-MBs + UTMD and Mp-MBs + UTMD groups. Conclusion. Vm-MBs or Mp-MBs combined with UTMD can effectively disrupt biofilms and protectively release antibiotics under ultrasound mediation, significantly reducing bacterial viability and improving the bactericidal effect of antibiotics. Cite this article: Bone Joint Res 2024;13(9):441–451

Aims. Periprosthetic joint infections (PJIs) are rare, but represent a great burden for the patient. In addition, the incidence of methicillin-resistant Staphylococcus aureus (MRSA) is increasing. The aim of this rat experiment was therefore to compare the antibiotics commonly used in the treatment of PJIs caused by MRSA. Methods. For this purpose, sterilized steel implants were implanted into the femur of 77 rats. The metal devices were inoculated with suspensions of two different MRSA strains. The animals were divided into groups and treated with vancomycin, linezolid, cotrimoxazole, or rifampin as monotherapy, or with combination of antibiotics over a period of 14 days. After a two-day antibiotic-free interval, the implant was explanted, and bone, muscle, and periarticular tissue were microbiologically analyzed. Results. Vancomycin and linezolid were able to significantly (p < 0.05) reduce the MRSA bacterial count at implants. No significant effect was found at the bone. Rifampin was the only monotherapy that significantly reduced the bacterial count on implant and bone. The combination with vancomycin or linezolid showed significant efficacy. Treatment with cotrimoxazole alone did not achieve a significant bacterial count reduction. The combination of linezolid plus rifampin was significantly more effective on implant and bone than the control group in both trials. Conclusion. Although rifampicin is effective as a monotherapy, it should not be used because of the high rate of resistance development. Our animal experiments showed the great importance of combination antibiotic therapies. In the future, investigations with higher case numbers, varied bacterial concentrations, and changes in individual drug dosages will be necessary to be able to draw an exact comparison, possibly within a clinical trial. Cite this article: Bone Joint Res 2022;11(3):143–151

Aims. Treatment outcomes for methicillin-resistant Staphylococcus aureus (MRSA) periprosthetic joint infection (PJI) using systemic vancomycin and antibacterial cement spacers during two-stage revision arthroplasty remain unsatisfactory. This study explored the efficacy and safety of intra-articular vancomycin injections for PJI control after debridement and cement spacer implantation in a rat model. Methods. Total knee arthroplasty (TKA), MRSA inoculation, debridement, and vancomycin-spacer implantation were performed successively in rats to mimic first-stage PJI during the two-stage revision arthroplasty procedure. Vancomycin was administered intraperitoneally or intra-articularly for two weeks to control the infection after debridement and spacer implantation. Results. Rats receiving intra-articular vancomycin showed the best outcomes among the four treatment groups, with negative bacterial cultures, increased weight gain, increased capacity for weightbearing activities, increased residual bone volume preservation, and reduced inflammatory reactions in the joint tissues, indicating MRSA eradication in the knee. The vancomycin-spacer and/or systemic vancomycin failed to eliminate the MRSA infections following a two-week antibiotic course. Serum vancomycin levels did not reach nephrotoxic levels in any group. Mild renal histopathological changes, without changes in serum creatinine levels, were observed in the intraperitoneal vancomycin group compared with the intra-articular vancomycin group, but no changes in hepatic structure or serum alanine aminotransferase or aspartate aminotransferase levels were observed. No local complications were observed, such as sinus tract or non-healing surgical incisions. Conclusion. Intra-articular vancomycin injection was effective and safe for PJI control following debridement and spacer implantation in a rat model during two-stage revision arthroplasties, with better outcomes than systemic vancomycin administration. Cite this article: Bone Joint Res 2022;11(6):371–385

Aims. Biofilm formation is intrinsic to prosthetic joint infection (PJI). In the current study, we evaluated the effects of silver-containing hydroxyapatite (Ag-HA) coating and vancomycin (VCM) on methicillin-resistant Staphylococcus aureus (MRSA) biofilm formation. Methods. Pure titanium discs (Ti discs), Ti discs coated with HA (HA discs), and 3% Ag-HA discs developed using a thermal spraying were inoculated with MRSA suspensions containing a mean in vitro 4.3 (SD 0.8) x 10. 6. or 43.0 (SD 8.4) x 10. 5. colony-forming units (CFUs). Immediately after MRSA inoculation, sterile phosphate-buffered saline or VCM (20 µg/ml) was added, and the discs were incubated for 24 hours at 37°C. Viable cell counting, 3D confocal laser scanning microscopy with Airyscan, and scanning electron microscopy were then performed. HA discs and Ag HA discs were implanted subcutaneously in vivo in the dorsum of rats, and MRSA suspensions containing a mean in vivo 7.2 (SD 0.4) x 10. 6.   or 72.0 (SD 4.2) x 10. 5.   CFUs were inoculated on the discs. VCM was injected subcutaneously daily every 12 hours followed by viable cell counting. Results. Biofilms that formed on HA discs were thicker and larger than those on Ti discs, whereas those on Ag-HA discs were thinner and smaller than those on Ti discs. Viable bacterial counts in vivo revealed that Ag-HA combined with VCM was the most effective treatment. Conclusion. Ag-HA with VCM has a potential synergistic effect in reducing MRSA biofilm formation and can thus be useful for preventing and treating PJI. Cite this article:Bone Joint Res. 2020;9(5):211–218

Aims. Methicillin-resistant Staphylococcus aureus (MRSA) can cause wound infections via a ‘Trojan Horse’ mechanism, in which neutrophils engulf intestinal MRSA and travel to the wound, releasing MRSA after apoptosis. The possible role of intestinal MRSA in prosthetic joint infection (PJI) is unknown. Methods. Rats underwent intestinal colonization with green fluorescent protein (GFP)-tagged MRSA by gavage and an intra-articular wire was then surgically implanted. After ten days, the presence of PJI was determined by bacterial cultures of the distal femur, joint capsule, and implant. We excluded several other possibilities for PJI development. Intraoperative contamination was excluded by culturing the specimen obtained from surgical site. Extracellular bacteraemia-associated PJI was excluded by comparing with the infection rate after intravenous injection of MRSA or MRSA-carrying neutrophils. To further support this theory, we tested the efficacy of prophylactic membrane-permeable and non-membrane-permeable antibiotics in this model. Results. After undergoing knee surgery eight or 72 hours after colonization, five out of 20 rats (25.0%) and two out of 20 rats (10.0%) developed PJI, respectively. Strikingly, 11 out of 20 rats (55.0%) developed PJI after intravenous injection of MRSA-carrying neutrophils that were isolated from rats with intestinal MRSA colonization. None of the rats receiving intravenous injections of MRSA developed PJI. These results suggest that intestinal MRSA carried by neutrophils could cause PJI in our rat model. Ten out of 20 (50.0%) rats treated with non-membrane-permeable gentamicin developed PJI, whereas only one out of 20 (5.0%) rats treated with membrane-permeable linezolid developed PJI. Conclusion. Neutrophils as carriers of intestinal MRSA may play an important role in PJI development. Cite this article:Bone Joint Res. 2020;9(4):152–161

Aims. To characterize the intracellular penetration of osteoblasts and osteoclasts by methicillin-resistant Staphylococcus aureus (MRSA) and the antibiotic and detergent susceptibility of MRSA in bone. Methods. Time-lapse confocal microscopy was used to analyze the interaction of MRSA strain USA300 with primary murine osteoblasts and osteoclasts. The effects of early and delayed antibiotic treatments on intracellular and extracellular bacterial colony formation and cell death were quantified. We tested the effects of cefazolin, gentamicin, vancomycin, tetracycline, rifampicin, and ampicillin, as well as agents used in surgical preparation and irrigation. Results. MRSA infiltrated bone-resident cells within 15 to 30 minutes. Penetration was most effectively prevented with early (i.e. 30 minutes) antibiotic administration. The combined administration of rifampicin with other antibiotics potentiated their protective effects against MRSA-induced cytotoxicity and most significantly reduced extracellular bacterial bioburden. Gentamicin-containing compounds were most effective in reducing intracellular MRSA bioburden. Of the surgical preparation agents evaluated, betadine reduced in vitro MRSA growth to the greatest extent. Conclusion. The standard of care for open fractures involves debridement and antibiotics within the first six hours of injury but does not account for the window in which bacteria penetrate cells. Antibiotics must be administered as early as possible after injury or prior to incision to prevent intracellular infestation. Rifampicin can potentiate the capacity of antibiotic regimens to reduce MRSA-induced cytotoxicity. Cite this article:Bone Joint Res. 2020;9(2):49–59

This prospective five-year study analyses the impact of methicillin-resistant Staphylococcus aureus (MRSA) on an Irish orthopaedic unit. We identified 318 cases of MRSA, representing 0.76% of all admissions (41 971). A total of 240 (76%) cases were colonised with MRSA, while 120 (37.7%) were infected. Patients were admitted from home (218; 68.6%), nursing homes (72; 22.6%) and other hospitals (28; 8.8%). A total of 115 cases (36.6%) were colonised or infected on admission. Many patients were both colonised and infected at some stage. The length of hospital stay was almost trebled because of the presence of MRSA infection. Encouragingly, overall infection rates have not risen significantly over the five years of the study despite increased prevalence of MRSA. However, the financial burden of MRSA is increasing, highlighting the need for progress in understanding how to control this resistant pathogen more effectively

Aims. Infection after surgery increases treatment costs and is associated with increased mortality. Hip fracture patients have historically had high rates of methicillin-resistant Staphylococcus aureus (MRSA) colonization and surgical site infection (SSI). This paper reports the impact of routine MRSA screening and the “cleanyourhands” campaign on rates of MRSA SSI and patient outcome. Methods. A total of 13,503 patients who presented with a hip fracture over 17 years formed the study population. Multivariable logistic regression was performed to determine risk factors for MRSA and SSI. Autoregressive integrated moving average (ARIMA) modelling adjusted for temporal trends in rates of MRSA. Kaplan-Meier estimators were generated to assess for changes in mortality. Results. In all, 6,189 patients were identified before the introduction of screening and 7,314 in the post-screening cohort. MRSA infection fell from 69 cases to 15 in the post-screening cohort (p < 0.001). The ARIMA confirmed a significant reduction in MRSA SSI post-screening (p = 0.043) but no significant impact after hand hygiene alone (p = 0.121). Overall SSI fell (2.4% to 1.5%), however deep infection increased slightly (0.89% to 1.06%). ARIMA showed neither intervention affected overall SSI (“cleanyourhands” -0.172% (95% confidence interval (CI) -0.39% to 0.21); p = 0.122, screening -0.113% per year, (95% CI -0.34 to 0.12); p = 0.373). One-year mortality after deep SSI was unchanged after screening (50% vs 45%; p = 0.415). Only warfarinization (OR 3.616 (95% CI 1.366 to 9.569); p = 0.010) and screening (OR 0.189 (95% CI 0.086 to 0.414); p < 0.001) were significant covariables for developing MRSA SSI. Conclusion. While screening and decolonization may reduce MRSA-associated SSI, the benefit to patient outcome remains unclear. Overall deep SSI remains an unsolved problem that has seen little improvement over time. Preventing other hospital-associated infections should not be forgotten in the fight against MRSA. Cite this article: Bone Joint J 2021;103-B(1):170–177

Aims. Infection complicating primary total knee arthroplasty (TKA) is a common reason for revision surgery, hospital readmission, patient morbidity, and mortality. Increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA) is a particular concern. The use of vancomycin as prophylactic agent alone or in combination with cephalosporin has not demonstrated lower periprosthetic joint infection (PJI) rates, partly due to timing and dosing of intravenous (IV) vancomycin administration, which have proven important factors in effectiveness. This is a retrospective review of a consecutive series of primary TKAs examining incidence of PJI, adverse reactions, and complications using IV versus intraosseous (IO) vancomycin at 30-day, 90-day, and one-year follow-up. Methods. A retrospective review of 1,060 patients who underwent TKA between May 2016 to July 2020 was performed. There were 572 patients in the IV group and 488 in the IO group, with minimal 30 days of follow-up. Patients were followed up at regularly scheduled intervals (two, six, and 12 weeks). No differences between groups for age, sex, BMI, or baseline comorbidities existed. The IV group received an IV dose of 15 mg/kg vancomycin given over an hour preceding skin incision. The IO group received a 500 mg dose of vancomycin mixed in 150 ml of normal saline, injected into proximal tibia after tourniquet inflation, before skin incision. All patients received an additional dose of first generation cephalosporin. Evaluation included preoperative and postoperative serum creatinine values, tourniquet time, and adverse reactions attributable to vancomycin. Results. Incidence of PJI with minimum 90-day follow-up was 1.4% (eight knees) in the IV group and 0.22% (one knee) in IO group (p = 0.047). This preliminary report demonstrated an reduction in the incidence of infection in TKA using IO vancomycin combined with a first-generation cephalosporin. While the study suffers from limitations of a retrospective, multi-surgeon investigation, early findings are encouraging. Conclusion. IO delivery of vancomycin after tourniquet inflation is a safe and effective alternative to IV administration, eliminating the logistical challenges of timely dosing. Cite this article: Bone Joint J 2021;103-B(6 Supple A):13–17

Objectives. Vancomycin and fosfomycin are antibiotics commonly used to treat methicillin-resistant Staphylococcus aureus (MRSA) infection. This study compares the in vitro inhibitory effects against MRSA of articulating cement spacers impregnated with either vancomycin or fosfomycin. Methods. Vancomycin-impregnated articulating cement spacers and fosfomycin-impregnated articulating cement spacers were immersed in sterile phosphate-buffered saline (PBS) solutions and then incubated. Samples were collected for bioactivity evaluation. The aliquots were tested for MRSA inhibition with the disc diffusion method, and the inhibition zone diameters were measured. The inhibition zone differences were evaluated using the Wilcoxon Rank Sum Test. Results. The vancomycin group had significantly larger inhibition zones than the fosfomycin group from day three through to completion of the fourth week of incubation (p < 0.001). The vancomycin group exhibited a MRSA inhibition zone up to four weeks but the fosfomycin group showed an inhibition zone for only three days and after that did not show the the potential to inhibit MRSA. Conclusion. This in vitro study found that the inhibitory effect of vancomycin-impregnated articulating cement spacers against MRSA outperformed fosfomycin-impregnated articulating cement spacers. Further comparing our results to other published reports suggests there might be a limitation of the disc diffusion bioassay to show a large inhibitory zone in a high concentration of a highly soluble antibiotic. Cite this article: V. Yuenyongviwat, N. Ingviya, P. Pathaburee, B. Tangtrakulwanich. Inhibitory effects of vancomycin and fosfomycin on methicillin-resistant Staphylococcus aureus from antibiotic-impregnated articulating cement spacers. Bone Joint Res 2017;6:132–136. DOI: 10.1302/2046-3758.63.2000639

The objective of this study was to determine the effectiveness of screening and successful treatment of methicillin-resistant Staphylococcus aureus (MRSA) colonisation in elective orthopaedic patients on the subsequent risk of developing a surgical site infection (SSI) with MRSA. We screened 5933 elective orthopaedic in-patients for MRSA at pre-operative assessment. Of these, 108 (1.8%) were colonised with MRSA and 90 subsequently underwent surgery. Despite effective eradication therapy, six of these (6.7%) had an SSI within one year of surgery. Among these infections, deep sepsis occurred in four cases (4.4%) and superficial infection in two (2.2%). The responsible organism in four of the six cases was MRSA. Further analysis showed that patients undergoing surgery for joint replacement of the lower limb were at significantly increased risk of an SSI if previously colonised with MRSA. We conclude that previously MRSA-colonised patients undergoing elective surgery are at an increased risk of an SSI compared with other elective patients, and that this risk is significant for those undergoing joint replacement of the lower limb. Furthermore, when an infection occurs, it is likely to be due to MRSA

Local antimicrobial therapy is an integral aspect of treating orthopaedic device related infection (ODRI), which is conventionally administered via polymethylmethacrylate (PMMA) bone cement. PMMA, however, is limited by a suboptimal antibiotic release profile and a lack of biodegradability. In this study, we compare the efficacy of PMMA versus an antibioticloaded hydrogel in a single- stage revision for chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI in. sheep. Antibiofilm activity of the antibiotic combination (gentamicin and vancomycin) was determined in vitro. Swiss alpine sheep underwent a single-stage revision of a tibial intramedullary nail with MRSA infection. Local gentamicin and vancomycin therapy was delivered via hydrogel or PMMA (n = 5 per group), in conjunction with systemic antibiotic therapy. In vivo observations included: local antibiotic tissue concentration, renal and liver function tests, and quantitative microbiology on tissues and hardware post-mortem. There was a nonsignificant reduction in biofilm with an increasing antibiotic concentration in vitro (p = 0.12), confirming the antibiotic tolerance of the MRSA biofilm. In the in vivo study, four out of five sheep from each treatment group were culture negative. Antibiotic delivery via hydrogel resulted in 10–100 times greater local concentrations for the first 2–3 days compared with PMMA and were comparable thereafter. Systemic concentrations of gentamicin were minimal or undetectable in both groups, while renal and liver function tests were within normal limits. This study shows that a single-stage revision with hydrogel or PMMA is equally effective, although the hydrogel offers certain practical benefits over PMMA, which make it an attractive proposition for clinical use

We examined the rates of infection and colonisation by methicillin-resistant Staphylococcus aureus (MRSA) between January 2003 and May 2004 in order to assess the impact of the introduction of an MRSA policy in October 2003, which required all admissions to be screened. Emergency admissions were treated prophylactically and elective beds ring-fenced. A total of 5594 admissions were cross-referenced with 22 810 microbiology results. The morbidity, mortality and cost of managing MRSA-carrying patients, with a proximal fracture of the femur were compared, in relation to age, gender, American Society of Anaesthesiologists grade and residential status, with a group of matched controls who were MRSA-negative. In 2004, we screened 1795 of 1796 elective admissions and MRSA was found in 23 (1.3%). We also screened 1122 of 1447 trauma admissions and 43 (3.8%) were carrying MRSA. All ten ward transfers were screened and four (40%) were carriers (all p < 0.001). The incidence of MRSA in trauma patients increased by 2.6% per week of inpatient stay (r = 0.97, p < 0.001). MRSA developed in 2.9% of trauma and 0.2% of elective patients during that admission (p < 0.001). The implementation of the MRSA policy reduced the incidence of MRSA infection by 56% in trauma patients (1.57% in 2003 (17 of 1084) to 0.69% in 2004 (10 of 1447), p = 0.035). Infection with MRSA in elective patients was reduced by 70% (0.56% in 2003 (7 of 1257) to 0.17% in 2004 (3 of 1806), p = 0.06). The cost of preventing one MRSA infection was £3200. Although colonisation by MRSA did not affect the mortality rate, infection by MRSA more than doubled it. Patients with proximal fractures of the femur infected with MRSA remained in hospital for 50 extra days, had 19 more days of vancomycin treatment and 26 more days of vacuum-assisted closure therapy than the matched controls. These additional costs equated to £13 972 per patient. From this experience we have been able to describe the epidemiology of MRSA, assess the impact of infection-control measures on MRSA infection rates and determine the morbidity, mortality and economic cost of MRSA carriage on trauma and elective orthopaedic wards

Orthopedic Device-Related Infections (ODRIs) are a major medical challenge, particularly due to the involvement of biofilm-encased and multidrug-resistant bacteria. Current treatments, based on antibiotic administration, have proven to be ineffective. Consequently, there is a need for antibiotic-free alternatives. Antimicrobial peptides (AMPs) are a promising solution due to their broad-spectrum of activity, high efficacy at very low concentrations, and low propensity to induce resistance. We aim to develop a new AMP-based chitosan nanogel to be injected during orthopedic device implantation to prevent ODRIs. Chitosan was functionalized with norbornenes (NorChit) through the reaction with carbic anhydride and then, a cysteine-modified AMP, Dhvar5, a peptide with potent antibacterial activity, even against methicillin-resistant Staphylococcus aureus (MRSA), was covalently conjugated to NorChit (NorChit- Dhvar5), through a thiol-norbornene photoclick chemistry (UV= 365 nm). For NorChit-Dhvar5 nanogels production, the NorChit-Dhvar5 solution (0.15% w/v) and Milli-Q water were injected separately into microfluidic system. The nanogels were characterized regarding size, concentration, and shape, using Transmission Electron Microscopy (TEM), Nanoparticle Tracking Analysis (NTA) and Dynamic light scattering (DLS). The nanogels antibacterial properties were assessed in Phosphate Buffer (PBS) for 6 h, against four relevant microorganisms (Pseudomonas aeruginosa, S. aureus and MRSA, and in Muller- Hinton Broth (MHB), 50% (v/v) in PBS, supplemented with human plasma (1% (v/v)), for 6 and 24 h against MRSA. The obtained NorChit-Dhvar5 nanogels, presented a round-shaped and ∼100 nm. NorChit- Dhvar5 nanogels in a concentration of 10. 10. nanogels/mL in PBS were capable of reducing the initial inoculum of P. aeruginosa by 99%, S. aureus by 99%, and MRSA by 90%. These results were corroborated by a 99% MRSA reduction, after 24 h in medium. Furthermore, NorChit-Dhvar5 nanogels do not demonstrate signs of cytotoxicity against MC3T3-E1 cells (a pre-osteoblast cell line) after 14 days, having high potential to prevent antibiotic-resistant infection in the context of ODRIs

We examined the incidence of infection with methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to the Leicester Royal Infirmary Trauma Unit between January 2004 and June 2006. The influence of MRSA status at the time of their admission was examined, together with age, gender and diagnosis, using multi-variant analysis. Of 2473 patients, 79 (3.2%) were MRSA carriers at the time of admission and 2394 (96.8%) were MRSA-negative. Those carrying MRSA at the time of admission were more likely to develop surgical site infection with MRSA (7 of 79 patients, 8.8%) than non-MRSA carriers (54 of 2394 patients, 2.2%, p < 0.001). Further analysis showed that hip fracture and increasing age were also risk factors with a linear increase in relative risk of 1.8% per year. MRSA carriage at admission, age and the pathology are all associated with an increased rate of developing MRSA wound infection. Identification of such risk factors at admission helps to target health-care resources, such the use of glycopeptide antibiotics at induction and the ‘building-in’ of increased vigilance for wound infection pre-operatively

Aim. Bacteriophages are remerging as alternative and adjunctive therapy for fracture-related infection (FRI). However, current administration protocols involve prolonged retention of a percutaneous draining tube with potential risk of developing superinfection. In this study, we applied a cocktail of in vitro evolved biofilm-targeting phages for Methicillin-resistant Staphylococcus aureus (MRSA) in a hydrogel platform co-delivering vancomycin. In vitro synergy and antibiofilm activity was assessed and a subsequent in vivo study was performed in a mouse FRI model with MRSA. Method. Two evolved bacteriophages (MRSA-R14 and COL-R23) with improved antibiofilm activity against a clinical isolate (MRSA3) were tested in combination with vancomycin and a carboxymethylcellulose (CMC) hydrogel in vitro and in vivo. MRSA3 bacterial biofilms were formed on sterile 4 mm sintered porous glass beads at 37 °C for 24 h. Biofilms were exposed to i-phage cocktail (10. 7. PFU/ml), ii-vancomycin at concentrations of 0.5, 1, 10 and 100 times the MIC, or iii-combination of phage cocktail and vancomycin. Recovered biofilm cells, were quantified by colony counting. The stability and release profiles of phage cocktail and vancomycin in co-delivery hydrogel were assessed in vitro for 8 days and 72 hrs, respectively, and subsequently tested in the treatment of 5-day-old MRSA3 infection of a femoral plate osteotomy in mice. Results. In vitro: The cocktail of evolved phages (10. 7. PFU/ml, 1:1) combined with 0.5 MIC vancomycin achieved 99.72% reduction in MRSA3 biofilm in vitro compared to the growth control. This combination was stable in the co-delivery hydrogel over 8 days. The release profile showed that 57% of phages and 80% of vancomycin were released after 72hrs, which was identical to the performance for gels loaded with phage or antibiotic alone. In the in vivo study, the bacterial load from animals that received co-delivery hydrogel and systemic vancomycin was significantly reduced compared to controls, animals that received systemic vancomycin and animals that received co-delivery hydrogel alone (p<0.05). Conclusions. Our study demonstrates the potential of using evolved phages in combination with vancomycin and hydrogel delivery systems for the treatment of MRSA-related infections. Further research in this area may lead to the development of specific therapies for biofilm-related infection

Aim. Antibiotics have limited activity in the treatment of multidrug-resistant or chronic biofilm-associated infections, in particular when implants cannot be removed. Lytic bacteriophages can rapidly and selectively kill bacteria, and can be combined with antibiotics. However, clinical experience in patients with surgical infections is limited. We investigated the outcome and safety of local application of bacteriophages in addition to antimicrobial therapy. Method. 8 patients (2 female and 6 male) with complex orthopedic and cardiovascular infections were included, in whom standard treatment was not feasible or impossible. The treatment was performed in agreement with the Article 37 of the Declaration of Helsinki. Commercial or individually prepared bacteriophages were provided by ELIAVA Institute in Tbilisi, Georgia. Bacteriophages were applied during surgery and continued through drains placed during surgery three times per day for the following 5–14 days. Follow-up ranged from 1 to 28 months. Results. Median age was 57 years, range 33–75 years. Two patients were diagnosed with a persistent knee arthrodesis infection, one chronic periprosthetic joint infection (PJI), one cardiovascular implantable electronic device (CIED) infection and four patients with left ventricular assist device (LVAD) infection. The isolated pathogens were multi-drug-resistant Pseudomonas aeruginosa (n=3), methicillin-sensitive Staphylococcus aureus (n=4), methicillin-resistant Staphylococcus aureus (MRSA) (n=1) and methicillin-resistant Staphylococcus epidermidis (MRSE) (n=1). 4 infections were polymicrobial. 5 patients underwent surgical debridement with retention of the implant, 1 patient with PJI underwent the exchange of the prosthesis and one patient with LVAD infection was treated conservatively. All patients received intravenous and oral antibiotic therapy and local application of bacteriophages. At follow-up of 12 month, 5 patients were without signs or symptoms of infection, whereas in one patient with LVAD infection, a relapse was observed with emergence of phage-resistant Pseudomonas aeruginosa. In this patient, no surgical revision was performed. Conclusions. Bacteriophage therapy may represent a valid additional approach, when standard antimicrobial and surgical treatment is not possible or feasible, including in difficult-to-treat infections. In our case series, 5 of 6 patients were infection free after 1 year. Further studies need to address the optimal bacteriophage administration route, concentration, duration of treatment and combination with antimicrobials

Between October 2001 and February 2002, 324 healthcare workers were screened for methicillin-resistant Staphylococcus aureus (MRSA) by nose and throat swabs. A positive finding led to activation of a standardised control programme for the affected person who was immediately excluded from work. Family members of those who were MRSA-positive were offered screening free of charge. An eradication programme was carried out in the permanent carriers. MRSA was found in 17 (5.3%) healthcare workers, 11 of whom proved to be permanent carriers, and six temporarily colonised. Three children of a positive healthcare worker showed nasopharyngeal MRSA, the acquisition of which occurred within the hospital. The standardised eradication programme for carriers was successful in most cases but failed in two individuals, whereupon systemic antibiotics were used successfully. The decolonised carriers, observed for more than one year, remained MRSA negative. Isolation precautions in hospitals do not always prevent hospital staff and their families from acquiring MRSA. The identification of affected employees is difficult because in most cases only asymptomatic colonisation occurs. Screening and eradication can be complicated and costly, and for the affected employees the occupational consequences can be far-reaching as they have no guaranteed legal protection

Aim. The rise of multidrug-resistant bacteria and the decreasing efficacy of antibiotic therapy in successfully treating biofilm-associated infections are prompting the exploration of alternative treatment options. This study investigates the efficacy of different bioactive glass (BAG) formulations - alone or combined with vancomycin - to eradicate biofilm. Further, we study the influence of BAG on pH and osmotic pressure as important factors limiting bacterial growth. Method. Different BAG-S53P4 formulations were used for this study, including (a) BAG-powder (<45 μm), (b) BAG-granules (500–800 μm), (c) a cone-shaped BAG-scaffold and (d) two kinds of BAG-putty containing granules, with no powder (putty-A) or with additional powder (putty-B), and a synthetic binder. Inert glass beads were included as control. All formulations were tested in a concentration of 1750 g/ml in Müller-Hinton-Broth. Targeted bacteria included methicillin-resistant Staphylococcus aureus (MRSA) and epidermidis (MRSE). Vancomycin was tested at the minimum-inhibitory-concentration for each strain (1 µg/ml for MRSA; 2 μg/ml for MRSE). To investigate the antibiofilm effect of BAG alone or combined with vancomycin, 3 hour-old MRSA or MRSE biofilms were formed on porous glass beads and exposed to BAG ± vancomycin for 24h, 72h and 168h. After co-incubation, biofilm-beads were deep-washed in phosphate-buffered saline and placed in glass vials containing fresh medium. Recovering biofilm bacteria were detected by measuring growth-related heat production at 37°C for 24h by isothermal microcalorimetry. Changes in pH and osmotic pressure over time were assessed after co-incubation of each BAG formulation in Müller-Hinton-Broth for 0h, 24h, 72h and 168h. Results. All BAG formulations showed antibiofilm activity against MRSA and MRSE in a time-dependent manner, where longer incubation times revealed higher antibiofilm activity. BAG-powder and BAG-putty-B were the most effective formulations suppressing biofilm, followed by BAG-granules, BAG-scaffold and finally BAG-putty-A. The addition of vancomycin had no substantial impact on biofilm suppression. An increase in pH and osmotic pressure over time could be observed for all BAG formulations. BAG-powder reached the highest pH value of 12.5, whereas BAG-putty-A resulted in the lowest pH of 9. Both BAG-putty formulations displayed the greatest increase on osmotic pressure. Conclusions. BAG-S53P4 has demonstrated efficient biofilm suppression against MRSA and MRSE, especially in powder-containing formulations. Our data indicates no additional antibiofilm improvement with addition of vancomycin. Moreover, high pH appears to have a larger antimicrobial impact than high osmolarity. Acknowledgements. This work was supported by PRO-IMPLANT Foundation (Berlin, Germany). The tested materials were provided by Bonalive Biomaterials Ltd (Turku, Finland)

Each year more than 70 billion standard units of antibiotic are prescribed to treat bacterial infections worldwide. In addition, at least 63,000 tons of antibiotics are consumed by livestock for growth promotion and disease prevention. The result of this overuse of antibiotics is a spiraling increase in resistance. In the United States and Europe, antibiotic resistant bacteria are responsible for more than 4 million infections and approximately 50,000 deaths annually. In addition, bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) have increased in prevalence in hospitals over the last three decades. Such bacteria are particularly problematic in postoperative infections, exacerbating treatment through the development of biofilms, especially on medical implants which are virtually impossible to treat without removal and replacement of the device. This presentation will show how non-invasive preclinical imaging (optical, PET and CT) is being used to better understand the establishment and development of bacterial infections in vivo, and how best to treat them. In particular, data will be shown as to how preclinical imaging can be used to monitor bacterial infections on orthopaedic implants, and how this technology might be translated into the clinic

Aims. Prosthetic joint infection (PJI) remains the most severe complication of arthroplasty. Failure of intensive, long-term antibiotic treatment for PJI often requires removal of the implant. Antibiotic failure is thought to be caused by biofilm and persister formation. Novel anti-biofilm and anti-persister strategies are urgently needed. Here, we investigated the effects of several antimicrobial peptides on the bacteria within antibiotic-treated biofilms in an in vitro mature biofilm model on abiotic surfaces. Methods. On polystyrene, a mature (7 day-old) methicillin-resistant Staphylococcus aureus (MRSA) biofilm was developed. Thereafter, bacteria in the biofilm were exposed to rifampicin and ciprofloxacin (both 10× >MIC) for three days. Surviving bacteria in the antibiotic-treated biofilm, presumed to include persisters, were exposed to increasing doses of the antimicrobial peptides SAAP-148, acyldepsipeptide 4 (ADEP4), LL-37 and pexiganan. SAAP-148 was further tested on antibiotic-treated mature biofilms on titanium/aluminium/niobium (TAN) discs and prosthetic joint liners. Results. Daily exposure of the mature biofilm for seven days with antibiotics resulted in a 4-log reduction of MRSA without elimination of the bacteria. The surviving bacteria within the biofilm were eliminated upon subsequent exposure to SAAP-148 and pexiganan but not with LL-37 ad ADEP4. Antibiotic treatment of mature biofilms on TAN discs followed by SAAP-148 also resulted in eradication of bacteria within the biofilm. SAAP-148 also fully eliminated bacteria within antibiotic-treated mature MRSA biofilms on an ex vivo liner of a prosthetic joint. Conclusions. A novel mature biofilm model has been developed in which the efficacy of antimicrobial peptides against bacteria, including persisters, residing within a biofilm was investigated. SAAP-148 and pexiganan were highly effective against the bacteria residing in antibiotic-exposed mature MRSA biofilms. This in vitro model system will be used to analyze the effects of novel antibiotic strategies and other anti-PJI agents

Aim. To investigate the ability of the bacteriophage Sb-1 to treat and prevent implant-associated infections due to methicillin-resistant Staphylococcus aureus (MRSA) in Galleria mellonella larvae implanted with a K-wire. Method. The stability of Sb-1 in G. mellonella larvae was investigated by injecting a phage titer of 10. 8. PFU and evaluating the presence of Sb-1 in hemolymph at different time points. For infection experiments, sterile stainless-steel K-wires (4 mm, 0.6 mm Ø) were implanted into larvae. Two days after implant, larvae were infected with MRSA ATCC 43300 (1×10. 5. CFU) and incubated at 37°C for further 2 days. Implanted-infected larvae were thus treated for 2 days (3×/day) with 10µL of: i) PBS; ii) Sb-1 (10. 7. PFU); iii) Daptomycin (4mg/kg), iv) PBS (24h)/Daptomycin(24h); v) Sb-1(24h)/Daptomycin(24h). To evaluate the prophylactic efficacy of Sb-1, an experiment based on phages or vancomycin (10mg/kg) administration, followed by MRSA infection of implanted larvae was performed. Both two days post-infection and post-treatment, K-wires were explanted, and the material was sonicated and plated for MRSA colony counting. Results. Sb-1 titer resulted stable in hemolymph of G. mellonella larvae for 6–8 h post-administration. Two days post-infection of K-wire implanted larvae, ≈5×10. 7. CFU/ml MRSA were found on the material. K-wires from larvae treated with Sb-1 or Daptomycin showed a MRSA CFU/ml reduction of ≈1 log compared to the CFU/ml values of the untreated control. The staggered administration Sb-1/Daptomycin determined higher CFU reduction (≈ 3.5 log). Prophylaxis with Sb-1 prevented MRSA infection of 7out of 10 larvae similarly to vancomycin. Conclusions. G. mellonella larvae implanted with K-wires are a suitable model to test antibiofilm formulations in vivo. Sb-1 phage is able to prevent implant-associated infection due to MRSA in larvae. Sequential combination of Sb-1 and Daptomycin strongly reduces the MRSA load on implanted K-wires

Background. Vancomycin and fosfomycin are antibiotic commonly used in Methicillin-resistant Staphylococcus aureus (MRSA) infection. This study compares the efficacy of articulating cement spacer implegnated with vancomycin and articulating cement spacer implegnated with fosfomycin to inhibit MRSA. Methods. Vancomycin implegnated articulating cement spacers and Fosfomycin implegnated articulating cement spacers were immersed in sterile phosphate buffered saline(PBS) and then incubated at 37 C. The samples were collected and change daily. Aliquots were tested for MRSA inhibition by disc diffusion method. The inhibition zones diameters were measured. Results. Vancomycin group showed an MRSA inhibition zone up to four weeks. However, Fosfomycin group showed inhibition zone in day 3 in some samples but after that no sample had the potential to inhibit MRSA. Conclusion. In this experiment. Vancomycin impregnated articulating cement spacers showed longer efficacy to inhibit MRSA when compared to Fosfomycin

Aim. The increasing incidence of orthopaedic methicillin-resistant Staphylococcus aureus (MRSA) infections represents a significant therapeutic challenge. Being effective against MRSA, the role of vancomycin may become more important in the orthopaedic setting in the years to come. Nonetheless, vancomycin bone and soft tissue penetration during infection remains unclear. We assessed the effect of a traumatically induced, implant-associated acute osteomyelitis on vancomycin bone penetration in a porcine model. Method. In eight pigs, implant-associated osteomyelitis was induced on day 0, using a Staphylococcus aureus strain. Following administration of 1,000 mg of vancomycin on day 5, vancomycin concentrations were obtained with microdialysis for eight hours in the implant bone cavity, in cancellous bone adjacent to the implant cavity, in subcutaneous adipose tissue (SCT) adjacent to the implant cavity, and in healthy cancellous bone and healthy SCT in the contralateral leg. Venous blood samples were also obtained. The extent of infection and inflammation was evaluated by post-mortem computed tomography scans, C-reactive protein serum levels and cultures of blood and swabs. Results. In relation to all the implant cavities, bone destruction was found. Ranging from 0.20 to 0.74, tissue penetration, expressed as the ratio of tissue to plasma area under the concentration-time curve from 0 to the last measured value, was incomplete for all compartments except for healthy SCT. The lowest penetration was found in the implant cavity. Conclusions. Staphylococcus aureus implant-associated osteomyelitis was found to reduce vancomycin bone penetration, especially in the implant cavity. These findings suggest that it may be unsafe to rely solely on vancomycin therapy when treating acute osteomyelitis. Particularly when metaphyseal cavities are present, surgical debridement seems necessary

Aim. Implant-associated osteomyelitis is a devastating complication with poor outcomes following treatment, especially when caused by antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). A large animal model of a two-stage revision to treat MRSA implant-associated osteomyelitis has been developed to assess novel treatments. A bioresorbable, thermo-responsive hyaluronan hydrogel (THH) loaded with antibiotics has been developed and our aim was to investigate it´s in vivo efficacy as a local antibiotic carrier compared to the current standard of care i.e. antibiotic-loaded polymethylmethacrylate (PMMA) bone cement. Method. 12 female, 2 to 4 year old, Swiss Alpine Sheep were inoculated with MRSA at the time of intramedullary nail insertion in the tibia to develop chronic osteomyelitis. After 8 weeks sheep received a 2-stage revision protocol, with local and systemic antibiotics. Group 1 received the gold standard clinical treatment: systemic vancomycin (2 weeks) followed by rifampicin plus trimethoprim/sulfamethoxazole (4 weeks), and local gentamicin/vancomycin via PMMA. Group 2 received local gentamicin/vancomycin delivered via THH at both revision surgeries and identical systemic therapy to group 1. Sheep were euthanized 2 weeks following completion of antibiotic therapy. At euthanasia, soft tissue, bone, and sonicate fluid from the hardware was collected for quantitative bacteriology. Results. Sheep tolerated the surgeries and both local and systemic antibiotics well. Gold standard of care successfully treated 3/6 sheep with a total of 10/30 culture-positive samples. All 6 sheep receiving antibiotic-loaded THH were successfully treated with 0/30 culture-positive samples, p=0.0008 gold-standard vs. hydrogel (Fisher's Exact). Conclusions. The clinical gold standard treatment was successful in 50% of sheep, consistent with outcomes reported in the literature treating MRSA infection. The antibiotic-loaded THH clearly outperformed the gold standard in this model. Superior efficacy of the THH is likely due to 1) the ability to administer local antibiotics at the both revision surgies due to the bioresorbable nature of the hydrogel, and 2) complete antibiotic release compared to bone cement, which is known to retain antibiotics. Our results highlight the potential of local delivered, biodegradable systems for antibiotics for eradicating implant-related infection caused by antibiotic-resistant pathogens. Acknowledgement. Funding provided by AO Trauma

Aim. This study aims to describe our department experience with single stage revision (SSR) for chronic prosthetic-joint infection (PJI) after total hip arthroplasty (THA) between 2005 and 2014 and to analyze success rates and morbidity results of patients submitted to SSR for infected THA according to pathogen. Method. We retrospectively reviewed our 10 years of results (2005–2014) of patients submitted to SSR of the hip combined with IV and oral antibiotic therapy for treatment of chronic PJI (at least 4 weeks of symptoms), with a minimum follow-up of four years (n=26). Patients were characterized for demographic data, comorbidities, identified germ and antibiotic therapy applied (empiric and/or targeted). Outcomes analyzed were re-intervention rate (infection-related or aseptic), success rate (clinical and laboratory assessment), length of stay, morbidity and mortality outcomes. Results. In this period, 26 single-stage revisions for chronic PJI of the hip were performed. Patients average age was 72 years (range 44–82). Ten patients were women. The average time of follow up was 69 months (range 4 to 12 years). The most commonly isolated bacteria were coagulase-negative Staphylococci (30%), methicillin-resistant Staphylococcus aureus (MRSA) (18%) and methicillin-sensitive Staphylococcus aureus (15%). It wasn't possible to identify the germ in 19% of the patients and other 23% were polymicrobial. Targeted antibiotic therapy was administered to 73% of patients and the most used targeted antibiotics were Vancomycin (53%), Linezolid (32%) and Rifampicin (21%). Mean length of stay was 25 days. In the follow-up period, 9 patients (35%) required a re-intervention for infection relapse. Two patients (8%) needed surgery because of persistent instability. During the follow-up period, the infection-free survival was 65% (33% for MRSA; 82% for coagulase-negative Staphylococci) and the surgery-free survival was 62%. Six patients (23%) died during the follow-up, all due to other medical conditions not related to hip infection. Conclusions. Our experience suggests that SSR is associated with good outcomes and low re-intervention rate, except in the case of infection due to MRSA. In this last group, the results were significantly poorer, what leads to suggest that a two-stage revision may be a better option. The potential advantages of a SSR include good rates of infection eradication, a decrease in surgical morbidity and mortality as well as a decrease in healthcare and global economic costs. As such, a one-stage aggressive surgical attitude in addition to targeted antibiotherapy seems to be a suitable solution in selected patients

Aim. We aimed to compare the in vitro antibacterial activity of Bioactive Glass (BAG) S53P4, which is a compound showing local antibacterial activity, to that of antibiotic-loaded polymethylmethacrylate (PMMA) against multidrug resistant bacteria from osteomyelitis (OM) and prosthetic joint infection (PJI) isolates. Method. We studied convenience samples of multidrug resistant (MDR) microorganisms obtained from patients presenting OM and prosthetic joint infection (PJI). Mixtures containing tryptic soy broth (TSB) and inert glass beads (2mm), BAG-S53P4 granules (0.5–0.8mm and <45 mm) and Gentamicin or Vancomycin-loaded PMMA beads were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus (MR-CoNS), Pseudomonas aeruginosa or Klebsiella pneumoniae isolates. Glass beads (2.0mm) were used as a control. Antibacterial activity was evaluated by means of time-kill curve, through seeding the strains on blood agar plates, and subsequently performing colony counts after 24, 48, 72, 96, 120 and 168 hours of incubation. Differences between groups were evaluated by means of two-way analysis of variance (ANOVA) and Bonferroni's t test. Results. Inhibition of bacterial growth started soon after 48 hours of incubation, reached zero CFU/ml between 120 and 168 hours of incubation for both antibiotic-loaded PMMA and BAG S53P4 groups, in comparison with inert glass (p< 0.05). No difference regarding time-kill curves between antibiotic-loaded PMMA and BAG S53P4 was observed. Moreover, despite no difference was observed between both Vancomycin - or Gentamicin-loaded PMMA and BAG groups, there was statistical difference between the effectiveness of all treatments (BAG included) against gram-positive cocci and gram-negative bacilli, the latter of which requiring longer time frames for the cultures to yield no bacterial growth. Conclusions. BAG S53P4 presented antibacterial properties as much as antibiotic-loaded PMMA for MDR bacteria producing OM and PJI, although presenting differences between its effectiveness against different bacterial groups

Aim. The aim of this systematic review was to determine all cultured bacteria, antibiotic strategies, and their outcome from literature describing treatment of FRI patients between 1990 and 2018. Methods. A systematic literature search was performed on treatment and outcome of FRI. All studies in English that described surgical patient series for treatment of FRI were included, using Medline, Embase, Web of Science, Cochrane, and Google Scholar. Publications before 1990 and studies that did not describe FRI patient treatment or did not report original data (e.g., reviews or meta-analyses) were excluded. Study selection and data collection were done by two authors independently. Main collected parameters were preoperative cultures, use of local antibiotics, postoperative antibiotic protocol, cultured microorganisms, and overall outcome of treatment, i.e., eradication of infection and bony union, recurrence, amputations, revisional surgery, and number of complications. Dichotomous data were pooled using Medcalc, and weighted means were calculated for continuous data using Excel. Results. 2,171 studies were identified. Of these, 110 studies were included, describing 119 patient series, in which 4561 patients (4614 fractures) were treated. The population was predominantly male (76%), and the main location of FRI was the tibia (69%). In 78 (71%) studies, 3,234 microorganisms were cultured, of which Methicillin-sensitive Staphylococcus aureus (MSSA) was found in 1,094 (34%) patients, followed by Coagulase-negative Staphylococci (CNS), 431 (13%), Methicillin-resistant Staphylococcus aureus (MRSA), 283 (9%), and Pseudomonas aeruginosa 276 (9%). Polymicrobial infections were present in 11% of patients. Local antibiotics were used in 63 (53%) patient series, with PMMA being the most frequent carrier (73%). Calcium-based cements were used in nine series (14%). Clear postoperative antibiotic protocols were described in only 39 (35%) studies and differed widely. Bony union and infection eradication were achieved in 92% (CI 90–94) of all patients. Recurrence was seen in 9% (CI 8–11), and amputation was required in 3% (CI 3–4) of patients. The effect of local antibiotics on overall outcome of FRI treatment was unclear. Conclusions. This systematic literature review clearly shows that standardized antibiotic treatment protocols for FRI patients are lacking and that internationally accepted guidelines are required. The data also confirm that S. aureus is the most common microorganism encountered in FRI. Due to the large heterogeneity of used local antibiotics and carriers, a reliable comparison was not feasible. Indications for the use of local antibiotics are unclear, and future prospective studies seem necessary

Aim. Most orthopedic infections are due to the microbial colonization of abiotic surfaces, which evolves into biofilm formation. Within biofilms, persisters constitute a microbial subpopulation of cells characterized by a lower metabolic-activity, being phenotipically tolerant to high concentrations of antibiotics. Due to their extreme tolerance, persisters may cause relapses upon treatment discontinuation, leading to infection recalcitrance hindering the bony tissue regeneration. Using isothermal microcalorimetry (IMC), we aimed to evaluate in vitro the presence of persisters in a methicillin-resistant Staphylococcus aureus (MRSA) biofilm after treatment with high concentrations of vancomycin (VAN) and their ability to revert to a normal-growing phenotype during incubation in fresh medium without antibiotic. Moreover, the ability of daptomycin to eradicate the infection by killing persisters was also investigated. Method. A 24h-old MRSA ATCC 43300 biofilm was exposed to 1024 µg/ml VAN for 24h. Metabolism-related heat of biofilm-embedded cells, either during or after VAN-treatment, was monitored in real-time by IMC for 24 or 48h, respectively. To evaluate the presence of VAN-derived “persisters” after antibiotic treatment, beads were sonicated and detached free-floating bacteria were further challenged with 100xMIC VAN (100 µg/ml) in PBS+1% Cation Adjusted Mueller Hinton Broth (CAMHB).. Suspensions were plated for colony counting. The resumption of persister cells' normal growth was analysed by IMC on dislodged trated cells for 15h in CAMHB. Activity of 16 µg/ml daptomycin was assessed against persister cells by colony counting. Results. When incubated with 1024 µg/ml VAN, MRSA biofilm produced undetectable heat, suggesting a strong reduction of cell viability and/or cellular metabolism. However, the same samples re-inoculated in fresh medium produced a detectable and delayed metabolism-related heat signal, similarly to that generated by persister cells. The following exposure to 100xMIC VAN resulted in neither complete killing nor bacterial growth, strongly supporting the hypothesis of a persistent phenotype. IMC analysis indicated that VAN-treated biofilm cells resumed normal growth with a ∼3h-delay, as compared to the untreated growth control. Daptomycin treatment yielded a complete eradication of persister cells selected after VAN treatment. Conclusions. Hostile environmental conditions (e.g. high antibiotic bactericidal concentrations) select for persister cells in MRSA biofilm after 24h-treatment in vitro. A staggered treatment vancomycin/daptomycin allows complete biofilm eradication. These results support the use in clinical practice of a therapeutic regimen based on the combined use of antibiotics to kill persisters and eradicate MRSA biofilms. IMC represents a suitable technique to detect persisters and characterize in real-time their reversion to a metabolically-active phenotype

Methicillin-resistant Staphylococcus aureus (MRSA) has become a ubiquitous bacterium in both the hospital and community setting. There are two major subclassifications of MRSA, community-acquired and healthcare-acquired, each with differing pathogenicity and management. MRSA is increasingly responsible for infections in otherwise healthy, active adults. Local outbreaks affect both professional and amateur athletes and there is increasing public awareness of the issue. Health-acquired MRSA has major cost and outcome implications for patients and hospitals. The increasing prevalence and severity of MRSA means that the orthopaedic community should have a basic knowledge of the bacterium, its presentation and options for treatment. This paper examines the evolution of MRSA, analyses the spectrum of diseases produced by this bacterium and presents current prevention and treatment strategies for orthopaedic infections from MRSA

Aim. Dexamethasone is often used as part of multimodal analgesia to prevent postoperative nausea and vomiting (PONV) and also to reduce postoperative pain. Because glucocorticoids have immunosuppressive and glucose-rising effects, the aim of current study was to examine if dexamethasone may be used safely in arthroplasty surgery. Methods. All consecutive total primary and revision hip and knee arthroplasties performed in the Hospital District of Helsinki and Uusimaa, Peijas Hospital were analyzed (n=18 872). Emergency operations, for example total hip arthroplasties for femur fractures, were also included. Prospective surveillance for postoperative infections was performed. All infections meeting the Musculoskeletal Infection Society definition for prosthetic joint infection (PJI) were included. Results. A total of 189 (1.0%) PJIs occurred: 0.8% after all primary arthroplasties and 1.9% after revision arthroplasties. The PJI rate after the emergency operations was 2.3 % (19/796). The PJI rate in the dexamethasone group was 1.0% (30/2 922) and in the non-dexamethasone group 1.0% (159/15 950), with no significant difference in the PJI incidence (P=0.849). The median time from the index operation to the infection was 16.0 (Q1–Q3 13.0–23.0) days. Total of 35 causative bacteria were cultured from the 30 PJI in dexamethasone group and 169 bacteria from the 159 PJI in non-dexamethasone group with no significant difference: Staphylococcus aureus (40.0% and 45.0%, respectively, P=1.000), Staphylococcus epidermidis (14.3% and 10.7%, P=0.375), other coagulase-negative staphylococci (11.4% and 11.8%, P=0.200), Streptococcus agalactiae (11.4% and 11.8%, P=0.695), Streptococcus betahemolyticus G (8.6% and 2.4%, P=0.081), other streptococci (0.0% and 4.1%, P=0.599), Enterococcus faecalis (2.9% and 5.3%, P=1.000), Enterobacter cloacae (2.9% and 3.6%, P=1.000), Pseudomonas aeruginosa (2.9% and 1.8%, P=0.502), and other bacteria (14.3% and 8.8%, P=0.544). Only one methicillin-resistant Staphylococcus aureus (MRSA) was detected in dexamethasone group. The proportion of polymicrobial PJIs was similar in both groups: 13.3% and 8.8%, respectively (p=0.495). Conclusions. In our study material, the use of 5–10mg dose of dexamethasone did not increase the incidence of postoperative PJI. The single 5–10 dose of dexamethasone may be safely used to prevent PONV and as part of multimodal analgesia on patients undergoing arthroplasty operation

Aim. The increase of antimicrobial resistance reduces treatment options for implant-associated infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Bacteriophages present a promising alternative to treat biofilm-related infections due to their rapid bactericidal activity and activity on multi-drug resistant bacteria. In this study, we investigated the synergistic activity of lytic bacteriophage Sb-1 with different antibiotics against MRSA biofilm, using a real-time highly sensitive assay measuring growth-related heat production (microcalorimetry). Methods. Rifampin, fosfomycin, vancomycin and daptomycin were tested alone and in combination with S. aureus specific phage, Sb-1, against MRSA (Staphylococcus aureus*). MRSA biofilm was formed on porous glass beads (Φ 4 mm, pore size 60 µm) and incubated for 24 h at 37° C in BHI. After 3 times washing biofilms were exposed first to different titers of bacteriophages, ranging from 102 to104 plaque-forming unite (pfu)/ml and after 24h treated again with subinhibitory concentration of antibiotics (corresponding to 1/4, 1/8, 1/16, 1/32 × MHICbiofilm). After 24h antibiotic treatment, the presence of biofilm on glass beads was evaluated by isothermal microcalorimetry for 48h. Heat flow (µW) and total heat (J) were measured. Results. MHICs of rifampin, fosfomycin, daptomycin and vancomycin when tested alone were 256 μg/ml, >4096 μg/ml, 128μg/ml and 2048μg/ml, respectively. Synergistic activity against biofilm MRSA was observed when vancomycin was tested at subinhibitory concentrations 512 μg/ml, 256 μg/ml, 128 μg/ml and 64 μg/ml in combination with subinhibitory titers of Sb-1 at 102, 103, 104 pfu/ml. Complete inhibition of heat production was observed only in combination with a higher titer of Sb-1 (104 pfu/ml). High synergistic activities were also observed in the presence of rifampin, fosfomycin and daptomycin. Conclusions. While MHICs of antibiotics against MRSA biofilm were above drug concentrations reachable in clinical practice, the co-administration with bacteriophage Sb-1 strongly reduced the antibiotic doses needed to eradicate MRSA biofilm. The use of bacteriophage and antibiotics in combination represent an effective strategy to treat implant-associated infections

Aim. North America is facing a rising epidemic involving strains of methicillin-resistant Staphylococcus aureus (MRSA) that, instead of being found almost exclusively in hospitals, are community-associated (CA-MRSA). These strains are aggressive, associated with musculoskeletal manifestations including osteomyelitis (OM), and septic arthritis (SA). We aimed to establish novel management algorithms for acute OM and SA in children. We investigated S.aureus susceptibilities to current first-line antimicrobials to determine their local efficacy. Method. The project was conducted at Nemours General Children Hospital in Florida, USA, following approval by the internal review board. A literature review was conducted. An audit of S.aureus antimicrobial sensitivities was completed over three years and compared against national standards. Susceptibilities of clindamycin, trimethoprim/sulfamethoxazole (TMP/SMX) and vancomycin were studied using local resistance ranges. Results. Two algorithms for acute OM and SA management were created adopting a multidisciplinary team approach from admission to discharge whilst differentiating higher risk patients within fast-track pathways. We analysed 532 microbiology results for antibiotic susceptibilities from 2012 to 2014. Overall, 51% of S.aureus infections were MRSA versus 49% methicillin-susceptible S.aureus (MSSA). Surprisingly, clindamycin resistance rates rose compared to 2005 (MRSA 7% in 2005 vs 39% currently, MSSA 20% vs 31% and total S.aureus resistance rate of 8% vs 35%, respectively). MRSA and MSSA isolates were near 100% sensitive to Vancomycin and TMP/SMX. No appropriate national standards existed. Conclusions. Multidisciplinary based algorithms were created for acute OM and SA treatment in children. Possible therapeutic roles for ultrasound guided aspiration and corticosteroids were highlighted in SA. Our audit revealed equal incidence of MSSA to MRSA, supporting national figures on falling MRSA. Interestingly, increased resistance of MSSA and MRSA was found towards recommended first line clindamycin, raising concern over its efficacy

Aim. To investigate the antimicrobial activity of a gentamicin-loaded bone graft substitute (GLBGS) in the prevention and eradication of bacterial biofilms associated with prosthetic joint infections (PJI). Method. The GLBGS (17,5 mg gentamicin/ml paste) with 40% hydroxyapatite/60% calcium sulfate. 1. was tested against biofilms of methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300, methicillin-susceptible S. aureus (MSSA) ATCC 29213, Escherichia coli Bj HDE-1, S. epidermidis ATCC 12228 and Enterococcus faecalis ATCC 19433. For prevention studies, glass beads and different combinations of GLBGS were co-incubated for 24h at 37°C in CAMH broth with 1–5 × 10. 6. CFU/mL of bacteria. For eradication, biofilms were formed on glass beads for 24h at 37°C in CAMH broth. Then, beads were incubated with different combinations of GLBGS in medium at 37°C for 24h. For microcalorimetric measurements, beads were placed in ampoules and heat flow (µW) and total heat (J) were measured at 37°C for 24h. The minimal heat inhibitory concentration (MHIC) was defined as the lowest gentamicin concentration reducing the heat flow peak by ≥90% at 24h. Results. The GLBGS showed a good activity against all tested strains in both biofilm prevention and eradication. All MHIC values are reported in Table 1. Lower MHICs were observed when GLBGS was tested against E. coli (9.6 µg/mL prevention and 19.2 µg/mL eradication) and S. epidermidis (86 µg/mL and 38.8 µg/mL, respectively). For both prevention and eradication of MSSA, GLBGS MHIC was 631 µg/mL. E. faecalis biofilm formation was prevented with 631 µg/mL and eradicated with double concentration. MRSA showed a higher resistance to GLBGS up to 2516 µg/mL, both in biofilm prevention and eradication. Conclusions. This GLBGS is a valid composite for the prophylaxis and treatment of PJI. Further studies will be performed to evaluate the activity of higher concentrations of GLBGS against MRSA. 1. CERAMENT™|G, BONESUPPORT AB, Sweden

Introduction. We report our mid-term results and risk factors of a two-stage revision using impaction bone grafting for an infected hip replacement. Methods. A two-stage revision using impacted cancellous allografs and cement was performed in 13 patients (7 total hip replacements, 6 femoral head replacements) with confirmed infection. The mean age of the patients at first stage operation was 63 years (range, 45–84 years). In the first stage, local antibiotics were added to customized cement beads and/or a cement spacer after removal of all components and radical debridement. In the second stage, impaction grafting was done using the X-change system (Exeter). Results. Of the patients, 8 underwent multiple operations to obtain evidence that infection had been overcome in the first stage, and of them, 6 had infection due to methicillin-resistant Staphylococcus aureus (MRSA). The mean duration from first stage operation to second stage revision was 8 months (range, 3–17 months). Only one patient suffered re-infection due to MRSA after second stage revision, which was not the original infecting agent, and the other 12 patients had satisfactory radiological outcomes. The success rate was 92% at the mean follow-up of 4 years (range, 1–10 years) after revision. Conclusion. Allograft bone was shown to be useful for infected hip replacement with a considerable loss of bone stock. We considered that control of MRSA infection is a key factor for successful outcome

Background. North America is facing a rising epidemic involving strains of methicillin-resistant Staphylococcus aureus (MRSA) that, instead of being found almost exclusively in hospitals, are community-associated (CA-MRSA). These strains are aggressive, associated with musculoskeletal manifestations including osteomyelitis (OM), and septic arthritis (SA). We aimed to establish novel management algorithms for acute OM and SA in children. We investigated S.aureus susceptibilities to current first-line antimicrobials to determine their local efficacy. Methods. The project was conducted at Nemours Children Hospital in Florida, USA, following approval by the internal review board. A literature review was conducted. An audit of S.aureus antimicrobial sensitivities was completed over three years and compared against national standards. Susceptibilities of clindamycin, trimethoprim/sulfamethoxazole (TMP/SMX) and vancomycin were studied using local resistance ranges. Results. Two algorithms for acute OM and SA management were created adopting a multidisciplinary team approach from admission to discharge whilst differentiating higher risk patients within fast-track pathways. We analysed 532 microbiology results for antibiotic susceptibilities from 2012 to 2014. Overall, 51% of S.aureus infections were MRSA versus 49% methicillin-susceptible S.aureus (MSSA). Surprisingly, clindamycin resistance rates rose compared to 2005 (MRSA 7% in 2005 vs 39% currently, MSSA 20% vs 31% and total S.aureus resistance rate of 8% vs 35%, respectively). MRSA and MSSA isolates were near 100% sensitive to Vancomycin and TMP/SMX. No appropriate national standards existed. Conclusions. Multidisciplinary based algorithms were created for acute OM and SA treatment in children. Possible therapeutic roles for ultrasound guided aspiration and corticosteroids were highlighted in SA. Our audit revealed equal incidence of MSSA to MRSA, supporting national figures on falling MRSA. Interestingly, incresed resistance of MSSA and MRSA was found towards recommended first line clindamycin, raising concern over its efficacy. Level of Evidence. 5

Introduction: Aside from a technical understanding, patients’ perceptions of, and the emotional associations they make with, their illness can influence the eventual outcome. We explored this in relation to bone and joint infections as these can have major impacts on patients in terms of reduced mobility, need for surgery and long-term antibiotic use. In particular we wanted. to assess how patients viewed their infections,. to see if infection with methicillin-resistant Staphylococcus aureus (MRSA) was different to non-MRSA infections, and. to explore the emotional associations of these infections. Methods: We adapted the Illness Perception Questionnaire of Weinman (1996) for this purpose. We focused on three domains: consequences, control/cure, and emotional responses. We asked all patients with osteomyelitis, septic arthritis or prosthetic joint infection attending the Liverpool Hospital Infectious Diseases Outpatient Clinic between May and August 2005 to complete the questionnaire. Results: Ninety-one patients completed the questionnaire. Thirty-nine had either MRSA infection or colonisation. Overall, most patients felt that their infection had made a major impact on their life (76%) or that their infection was very serious (79%). This negative response was independently associated with younger age and having MRSA (either infection or colonisation). Patients with prosthetic joint infections felt they had reduced sense of control and likelihood of cure. Conclusions: Bone and joint infections have a major psychological impact on patients, especially the young, those with MRSA and those with prosthetic joint infections. Health care professionals should take account of these emotional responses in order to optimise their therapeutic relationship with patients

The objective of our study was to assess the efficacy of infection control measures (pre-admission screening and patient segregation) on reducing inpatient exposure to methicillin-resistant Staphylococcus aureus (MRSA). A prospective case-control study was undertaken, analysing all admissions to three wards over an 83-month period from September 1995 to July 2002 inclusive (a total of approximately 34 000 patients). An orthopaedic ward with active infection control measures was compared with two controls, an orthopaedic ward with no measures and a general surgical ward with no measures. A statistical analysis was performed of the difference between the 3 wards in numbers of new cases of MRSA infection or colonisation. There was a statistically significant difference in numbers of new cases between the ward with the active infection control measures and the two control wards. The infection control methods described are shown to reduce the exposure of patients to MRSA, which is of importance in orthopaedics, and has further benefits that may be applied in other surgical specialties, notably the choice of antibiotic used with the associated risk of side-effects of the specific anti-MRSA agents, the cost for surgical prophylaxis and patients’ confidence in the admitting surgical unit. As a useful by-product, such segregated inpatient beds are effectively ring-fenced, ensuring availability even during a hospital bed-shortage

Implantation of antibiotic-loaded beads is accepted as an efficient option for local antibiotic therapy in orthopedic-related infections. However, recent reports have emphasized the bacteria growth persistence on antibiotic-impregnated bone cement. Hence, the aim of this study was to elaborate if bacterial adherence and growth could be determined on explanted gentamicin- and gentamicin-vancomycin-loaded beads after infection eradication. 18 chains of antibiotic-loaded beads (11 gentamicin-, 7 gentamicin-vancomycin-loaded) were examined. Indications for primary beads implantation included postoperative infections after total hip or knee arthroplasty, rotator cuff reconstruction, chronic foot osteomyelitis, anterior cruciate ligament reconstruction and dorsal spondylodesis. Among the isolated organisms, Staphylococcus epidermidis, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) were the most frequent ones. In 4 cases (3 × S. epidermidis, 1 × MRSA) bacteria growth persistence could be determined on the beads. S. epidermidis-strains persisted only on gentamicin-loaded beads, MRSA could grow on gentamicin-vancomycin-impregnated cement. In one case, the emergence of a gentamicin-resistant S. epidermidis-strain could be observed despite preoperative susceptibility. Bacteria growth persistence on bone cement is a hazardous problem in the orthopedic surgery and should therefore be born in mind. Adherence to cement can lead to emergence of bacteria resistance despite preoperative antibiotic susceptibility and might result in clinical recurrence of infection

Methicillin-resistant Staphylococcus aureus (MRSA) has increased in prevalence and significance over the past ten years. Studies have shown rates of MRSA in Trauma and Orthopaedic populations to be from 1.6% to 38%. Rates of MRSA are higher in long term residential care. It has been Department of Health policy to screen all Trauma and Orthopaedic patients for MRSA since 2001. This study audited rates of MRSA screening in patients who presented with fractured neck of femur treated with Austin Moore hemi-arthroplasty over the course of one year. Rates of MRSA carriage and surgical site infection (SSI) were derived from the computerised PAS system and review of case notes. 9.8 % of patients were not screened for MRSA at any time during their admission. The rate of MRSA carriage within the study population was 9.2%. The MRSA SSI rate was 4.2%. MRSA infections are associated with considerable cost and qualitative morbidity and mortality. There is good evidence for the use of nasal muprocin and triclosan baths in reducing MRSA. Single dose Teicoplanin has been shown to be as effective as traditional cephalosporin regimes. There is new guidance for the use of prophylactic Teicoplanin for prevention of SSI. We should consider introducing both topical and antimicrobial MRSA prophylaxis

Periprosthetic infection remains a clinical challenge that may lead to revision surgeries, increased spending, disability, and mortality. The cost for treating hip and knee total joint infections is anticipated to be $1.62 billion by 2020. There is a need for implant surface modifications that simultaneously resist bacterial biofilm formation and adhesion, while promoting periprosthetic bone formation and osseointegration. In vitro research has shown that nanotextured titanium promotes osteoblast differentiation, and upregulates metabolic markers of osteoblast activity and osteoblast proliferation. In vivo rat studies confirmed increased bone-implant contact area, enhanced de novo bone formation on and adjacent to the implant, and higher pull-out forces compared to non-textured titanium. The authors have advanced a benign electrochemical anodization process based on ammonium fluoride that creates a nanotube surface in as little as 10 minutes (Fig. 1), which can also integrate antibacterial nanosilver (Fig. 2). The work reported here summarizes in vitro post-inoculation and in vivo post-implantation studies, showing inherent inhibition of methicillin-resistant Staphylococcus aureus (MRSA) by titanium surfaces with nanotubes (TiNT), nanotubes with nanosilver (TiNT+Ag), plain (Ti), and thermal plasma sprayed (TPS) titanium. Ti6Al4V was the base material for all surfaces. In vitro studies evaluated Ti, TPS, four TiNT groups with varying nanotube diameters (60nm, 80nm, 110nm, 150nm), and TiNT+Ag. After seeding with MRSA (10. 5. , 10. 6. , and 10. 8. CFU/mL), the 110nm diameter nanotubes showed MRSA inhibition up to three-orders of magnitude lower than the Ti and TPS surfaces at 2, 6, and 48 hours. Following on the in vitro results, New Zealand White rabbits underwent a bilateral implantation of intramedullary tibial implants of the four material groups (4 mm outside diameter; 110nm NT diameter on TiNT and TiNT+Ag implants). One intramedullary canal was inoculated with clinically-derived MRSA (10. 5. CFU in broth) at the time of implantation; one canal had only culture media introduced (control). At a 2-week endpoint, limbs were harvested for analysis, including implant sonication with sonicant bacterial cultured, histology, and microcomputed chromatography. In the sonicant analysis cohort, TPS showed the lowest average MRSA count, while TiNT and TiNT+Ag were the highest. There was one sample each of TPS, TiNT and TiNT+Ag that showed no MRSA. After an additional 24-hour implant incubation, the TiNT and TiNT+Ag samples had no bacteria, but the TPS grew bacteria; therefore, the authors hypothesize that MRSA more readily releases from the TiNT and TiNT+Ag implants during sonication, indicating weaker biofilm adhesion and development. Histologic analysis is currently underway. In a therapeutic experiment, rabbits underwent bilateral implantation, followed by 1 week of infection development, and then 1 week of vancomycin treatment. At the endpoint, implants were sonicated and bacteria was quantified from the sonicant. TiNT showed viable MRSA at only 30% that of TPS-coated levels, while TiNT+Ag implants showed viable MRSA at only 5% that of TPS-coated levels (Fig. 3). These early results indicate that the TiNT and TiNT+Ag surfaces have some inherent antibacterial activity against MRSA, which may increase the efficacy of systemic antibiotic treatments in the setting of periprosthetic joint infections

To describe the prevalence and incidence of Methicillin-resistant Staphylococcus aureus (MRSA) colonisation during the patient journey for patients admitted to orthopaedic and trauma wards, we carried out a prospective audit at the University Hospital of North Staffordshire NHS Trust, England. The Study Population comprised patients admitted to the trauma and elective orthopaedic wards, with an expected stay of 48 hours or more between March and May 2003. Patients were swabbed for MRSA colonisation on ward admission, transfer to another ward and discharge from hospital. Elective patients undergoing major joint surgery were also swabbed at a pre-operative assessment clinic. Colonised patients were treated depending on individual risk assessment. Five hundred and fifty-nine eligible patients were admitted to hospital. Of these, 323 (101 elective, 192 trauma and 30 non-orthopaedic) patients were included in the study, of whom 28 elective patients (28%), 43 trauma patients (22%), and seven non-orthopaedic patients (23%) were colonised with MRSA at any time during the audit period. Of the 80 patients identified as negative for MRSA colonisation at pre-assessment screening and included in the audit, ten (9.5%) were found to be colonised on admission. There is a high prevalence of MRSA colonisation in patients admitted to the orthopaedic and trauma wards in our setting. A policy of pre-admission screening, though able to identify MRSA carriage does not guarantee that patients are not colonised in the period between screening and admission. Consideration should be given to screening all patients for MRSA who are admitted to an orthopaedic ward

Nosocomial infection with methicillin-resistant Staphylococcus aureus (MRSA) is on the increase and is expensive to treat. MRSA surgical wound infection may have disastrous consequences, particularly in an orthopaedic setting. We studied the rate of MRSA colonization in an important subgroup of orthopaedic patients. 50 nursing home residents were retrospectively reviewed with regard to their MRSA status on admission to an orthopaedic ward with fractured neck of femur. As is policy in our institution, all patients from nursing homes or other institutions are screened for MRSA on admission. Of the 50 nursing home patients requiring a hemi-arthroplasty, 16%(8) were MRSA positive. 2%(1/50) acquired MRSA infection while I hospital, while the remaining 14%(7/50) were carriers on admission. 4%(2/50) developed sepsis postoperatively, followed by multiorgan failure and death. 4% had their MRSA cleared prior to discharge, while 8% remained positive on discharge. All patients undergoing hemiarthroplasty received cefuroxime, unless allergic, as prophylaxis at induction. These findings of considerable MRSA carriage in nursing home patients is particularly relevant today, as the number of patients in nursing homes continues to grow as the population ages. The patient population in nursing homes is susceptible to infection because of the physiological changes that occur with ageing, the underlying chronic diseases of the patients and the institutional environment within which residents socialize and live. Nursing home residents presenting to orthopaedic units for surgery are a unique group in repairing careful consideration

One of the most challenging complications in orthopedic trauma surgery is the development of infection. Improved infection prophylaxis could be achieved by providing local delivery of antibiotics directly to the tissue-implant interface. Especially implant-associated bone infections caused by antibiotic-resistant pathogens pose significant clinical challenges to treating physicians. Prophylactic strategies that act against resistant organisms, such as methicillin-resistant Staphylococcus aureus (MRSA), are urgently required. The objective of this experimental study was to determine the efficacy of a biodegradable Polymer-Lipid Encapsulation MatriX (PLEX) loaded with the antibiotic doxycycline as a local prophylactic strategy against implant-associated osteomyelitis in a humeral non-fracture rabbit model. Activity of the PLEX-doxycycline-coating was tested against both a doxycycline susceptible (doxyS) methicillin-susceptible S. aureus (MSSA) as well as a doxycycline-resistant (doxyR) MRSA. In a rabbit intramedullary (IM) nail-related infection model, twelve rabbits received an inoculum of a doxyS MSSA direct into the medullary cavity of the humerus. After inoculation, animals received either a PLEX-doxycycline-coated nail, or an uncoated nail. The animals were observed for four weeks. Upon euthanasia, quantitative bacteriology was performed to determine bacterial load in tissues and biofilm formation on the implant. A second study was performed with sixteen rabbits receiving a DoxyR MRSA inoculum, again in coated and uncoated groups. In vitro elution studies revealed that 25% of the doxycycline was released from the PLEX-coated implants within the first day, followed by a 3% release per day up to day 28. Quantitative bacteriology revealed the presence of osteomyelitis in all animals receiving an uncoated nail in both the MSSA and the DoxyR MRSA studies (figure). All rabbits receiving a PLEX-doxycycline-coated nail were culture negative in the doxyS MSSA-group and the surrounding bone displayed a normal physiological appearance in both histological sections and radiographs. In the doxyR MRSA inoculated rabbits, a statistically significant reduction in the number of culture-positive samples was observed for the PLEX-doxycycline-coated group when compared to the animals that had received an uncoated nail, although the reduction in bacterial burden did not reach statistical significance. Improved prophylaxis against infection in trauma and orthopedic implant surgery is clearly required today. In this study, we investigated a PLEX-doxycycline-coated IM nail in a humeral non-fracture rabbit model. The PLEX-doxycycline coating on titanium alloy implants provided complete protection against implant-associated MSSA osteomyelitis, and resulted in a significant reduction in the number of culture positive samples when challenged with a doxycycline-resistant MRSA

Aim. Treatment principles of chronic osteomyelitis include debridement, clean sampling, excision of dead bone, stabilization, dead space management, soft tissue closure and systemic antibiotic therapy. Dead space management becomes very complicated, if the bone infection is caused by multi-resistant bacteria. The aim of this investigation was to evaluate the effect of a new vancomycin-loaded hydroxyapatite / calcium sulfate composite. *. in the treatment of chronic osteomyelitis (OM) caused by multi-resistant bacteria. Method. From June 2015 to November 2015, 7 patients (4 males, 3 females, average age 52.6y) were treated according to the above mentioned principles using the new vancomycin-loaded hydroxyapatite / calcium sulfate composite. *. Infections were caused by methicillin-resistant Staphylococcus aureus (MRSA), multi-resistant Staphylococcus epidermidis (MRSE) and polymicrobial, vancomycin-sensitive bacteria. We used a two-stage protocol with debridement, excision of bone and external stabilization in the first stage, followed by bone defect reconstruction. To fill the residual bone defects, in 3 patients the new vancomycin-loaded hydroxyapatite / calcium sulfate composite. *. (10mL) was used on its own and in 4 patients combined with 18mL of an unloaded calcium sulfate / hydroxyapatite composite. **. Post-operative follow-up was evaluated clinically and by radiographs and CT scans at 6, 14 and 24 weeks. Results. In 6 of 7 patients rapid control of infection was achieved. Soft tissue reactions and prolonged white wound drainage (caused by calcium sulfate dissolution) was seen in 3 of 7 patients. In 6 of 7 patients recurrence of infection has not been observed so far. Radiographs showed different elution intervals of the radiocontrast agent (Iohexol), depending on anatomical location. Bone remodelling or replacement of the composite by new bone was not uniform in the patients and showed specific radiographic signs. In addition to the so-called „puddle sign“, we found septae, membranes, vacuoles and sometimes arc-like structures. Therefore, we suggest the name “arc-sign” for these formations. Conclusions. During the follow-up of the first 7 patients treated with the unloaded calcium sulfate / hydroxyapatite composite. **. in 6 of 7 cases no recurrence of infection was observed. This is very promising in the difficult situation of bone infections caused by multi-resistant bacteria. Follow-up radiographs and CT-scans showed specific patterns during the resorption of the composite and the formation of new bone, which have not been described in other bone graft substitutes so far. The bone defects are not completely filled yet, but the affected bones are clinically stable and patients can ambulate with full weight bearing

Purpose: The purpose of this study was to evaluate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) isolates in the Orthopaedic Department of a new University Hospital, two years from its opening. Material and Methods: Forty-three consecutive S. aureus isolates, collected from cultures (pus 90%) from consecutive orthopaedic inpatients were included in the study. Resistance to antimicrobial agents was assessed by the disk diffusion method. The mecA-gene was detected by PCR assay, whereas molecular typing of the isolates was performed by PFGE. Results: Only 5 of the 43 strains (11.6%) expressed high level resistance to oxacillin (MIC ≥ 64mg/L). All these isolates possessed mecA-gene and exhibited resistance, except oxacillin, to more than four classes antimicrobial groups. The remaining 38 isolates (34 beta-lactamase positive) were susceptible to oxacillin (MIC ≤ 2mg/D, and expressed a less resistant type than that of MRSA. Molecular typing by PFGE showed apparent heterogeneity among isolates and the absence of predominant clones. Conclusions: The 11.6% prevalence of MRSA is well below the reported average in the literature. Apparently the isolates originated from different sources of contamination. All patients had previous hospitalizations, where they acquired the infections and subsequently transferred the MRSAs to our department. Precautions and measures taken in the wards limited the spread and dissemination of the isolates as demonstrated by the heterogeneity and the absence of predominant clones. These findings further reiterate the value of the low-cost, standard preventive procedures to control nosocomial infections in a high-risk orthopaedic department

Prosthetic joint infection (PJI) is an increasing problem and management commonly involves prosthesis removal with serious consequences. Biofilm-forming staphylococci are the most common causative organisms with Staphylococcus aureus being most virulent and methicillin-resistant Staphylococcus aureus (MRSA) more than doubling the infection mortality rate. Bacterial adhesion is an essential primary event in biofilm formation and infection establishment. The development of a novel combination vaccine programme to prevent staphylococcal PJI by directing antibody against factors involved in adhesion and biofilm formation, and investigation of S. aureus binding-domains as potential vaccine components for adhesion inhibition is described. Selected target antigens included the S. aureus fibronectin-binding protein (FnBP) and iron-regulated surface determinant (IsdA), which have been shown to be important for infection establishment and predominantly bind to host fibronectin and fibrinogen respectively. Escherichia coli clones harbouring recombinant S. aureus binding-domain DNA sequences were used for expression and purification of antigen domains. In vitro antibody evaluation determined whether immune inhibition of bacteria - ligand binding can significantly impact on attachment to plasma-conditioned biomaterial (in presence of other bacterial ligands). Adhesion of homologous and heterologous (MRSA PJI isolate) S. aureus to plasma-conditioned steel was significantly reduced (approximately 50 percent average reduction, p < 0.0001) when pre-exposed to anti-rFnBP-A antiserum (with pre-immune serum control) that was 50-fold more dilute than the actual titre from immunisation. Inhibition was related to ligand presence but not staphylococcal Protein A, and reduced adhesion was not observed with the mutant strain, indicating specific inhibitory antibody involvement, and demonstrating for the first time the potential of rFnBP-A for prevention of S. aureus PJI. Adhesion-inhibitory activity was also observed with a purified IgG-fraction of rIsdA antiserum but this activity appeared to be masked by non-IsdA - related interactions when non-IgG - purified antiserum was assessed

Introduction. Resistant organisms are difficult to eradicate in infected total knee arthroplasty, and treatment of methicillin-resistant Staphylococcus aureus (MRSA) is especially challenging. Whereas most surgeons use antibiotic-impregnated cement during revision to treat infection, the delivery of the drug in adequate doses is limited in penetration and duration. This study presents the 2- to 8-year prospective results of one-stage revision and intraarticular antibiotic infusion protocol used to treat MRSA. Methods. Eighteen knees (18 patients) with methicillin-resistant Staphylococcus aureus were treated between January 2001 and January 2007 with one-stage revision protocol that included débridement, uncemented revision of total knee components, and intraarticular infusion of 500 mg vancomycin via Hickman catheter once or twice daily for 6 weeks. (Figure 1) No intravenous antibiotics were used after the first 24 hours. Serum vancomycin levels were monitored to maintain levels between 3 and 10 μg/mL. The mean serum vancomycin peak concentration was 6 ± 2 μg/mL and the mean serum vancomycin trough concentration was 3 ± 1 μg/mL at 2 weeks postoperative. Results. Knee synovial fluid peak and trough vancomycin levels were measured in two knees. Synovial fluid peak concentrations were 10,233 μg/mL and 20,167 μg/mL and trough concentrations were 724 μg/mL and 543μg/mL, respectively. Minimum followup was 27 months (range, 27-75 months). Mean followup was 62 months, (range, 27–96 months). At 2-year followup, mean Knee Society score was 83 ± 9. No radiographic evidence of implant migration has occurred. One knee became reinfected with methicillin-resistant Staphylococcus aureus and was reoperated at 5 months. A necrotic bone segment was found, the knee was debrided and revised, and the antibiotic infusion protocol was readministered. The knee remained free of infection at 42 months postoperatively. Conclusions. One-stage revision with uncemented components and 6 weeks intraarticular vancomycin administration safely and effectively treated MRSA-infected TKA with no apparent complications

Introduction: Biodegradable systems releasing antibiotics are promising candidates for the management of chronic osteomyelitis. Gentamicin and fluoroquinolones are the commonest antibiotics applied with these systems. The effectiveness of a new system from polymerized dilactide (PLA) with incorporated linezolid has been investigated in a rabbit model for treating osteomyelitis by methicillin-resistant Staphylococcus Aureus (MRSA). Methods: The PLA – Linezolid system was made after thorough stirring 2gr of polymer with 100 mg of linezolid. Experimental osteomyelitis was established in 40 rabbits by a modification of the Norden model. Methicillin-resistant Staphylococcus aureus (MRSA) was applied as the test isolate. After drilling a hole in the upper right femur, the isolate was inoculated along with a thin needle working as a foreign body. After three weeks the needle was removed and cultured and PLA-Linezolid system was implanted in half of the animals. Animals were sacrificed at regular time intervals and tissue around the site of implantation was sent for histologic examination and quantitative cultures. Results: At 2 – 4 – 6 – 8 – 10 weeks time after removal of the needle results (mean values) were as follows (Controls/PLA-Linezolid): Log10 (cfu/g) at infection site: 2.99/5.68 – 3.44/3.20 – 3.22/2.39 – 1.00/1.27 – 1.00/1.00 respectively and Δlog10 (cfu/g) compared to start: −0.05/−3.23 – 0.23/0.13 – 0.05/0.93 – 1.34/1.09 – 3.31/3.34 respectively. Histology confirmed the previous mentioned results, showing an early decrease following by late recurrence of the infectious reaction at the animals that PLA-Linezolid system was used. Conclusions: It is concluded that the applied system achieved an early decrease of the tissue bacterial load which was not maintained until late on follow-up. This might be explained by the bacteriostatic mode of action of linezolid

Introduction:. Periprosthetic infections that accompany the use of total joint replacement devices cause unwanted and catastrophic outcomes for patients and clinicians. These infections become particularly problematic in the event that bacterial biofilms form on an implant surface. Previous reports have suggested that the addition of Vitamin E to ultra-high-molecular-weight polyethylene (UHMWPE) may prevent the adhesion of bacteria to its surface and thus reduce the risk of biofilm formation and subsequent infection. 1–3. In this study, Vitamin E was blended with two types of UHMWPE material. It was hypothesized that the Vitamin E blended UHMWPE would resist the adhesion and formation of clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) biofilms. Methods and Materials:. Five sample types were manufactured, machined and sterilized (Table 1). To determine if MRSA biofilms would be reduced or prevented on the surface of the Vitamin E (VE) loaded samples (HXL VE 150 kGy and HXL VE 75 kGy) in comparison to the other three clinically relevant material types, each was tested for biofilm formation using a flow cell system. 4. Direct Bacterial Quantification – An n = 7 samples of each material type were placed individually into a chamber of the flow cell. A solution of 10% modified brain heart infusion (BHI) broth containing 10. 5. MRSA cells/mL was flowed through each chamber. Using previously established protocols,. 4–7. after 48 hours of growth, each sample was removed, and the number of colony forming units (CFU) determined using a 10-fold dilution series. SEM Imaging – Using the same protocol as above, after the 48-hour incubation period, an n = 7 of each material type were fixed in 2.5% glutaraldehyde, dehydrated in ascending concentrations of ethanol, coated with carbon and imaged using scanning electron microscopy (SEM). Results:. Results indicated that the Vitamin E blended materials did not resist the attachment/formation of MRSA biofilms to any greater degree than the other three material types. All materials had greater than 10. 7. CFU/cm. 2. (Figure 1). SEM images corroborated with the quantification data (Figure 2). Discussion:. In contrast to previously published results,. 1–3. these data indicated that Vitamin E blended UHMWPE may not have the ability to prevent biofilm formation of a clinical MRSA isolate from occurring