Aims. Calcium sulphate (CaSO. 4. ) is a resorbable material that can be used simultaneously as filler of a dead space and as a carrier for the local application of antibiotics. Our aim was to describe the systemic exposure and the wound fluid concentrations of vancomycin in patients treated with vancomycin-loaded CaSO. 4. as an adjunct to the routine therapy of bone and joint infections. Patients and Methods. A total of 680 post-operative blood and 233 wound fluid samples were available for analysis from 94 implantations performed in 87 patients for various infective indications. Up to 6 g of vancomycin were used. Non-compartmental pharmacokinetic analysis was performed on the data from 37 patients treated for an infection of the hip. Results. The overall systemic exposure remained within a safe range, even in patients with post-operative renal failure, none requiring removal of the pellets. Local concentrations were approximately ten times higher than with polymethylmethacrylate (PMMA) as a carrier, but remained below reported cell toxicity thresholds. Decreasing concentrations in wound fluid were observed over several weeks, but remained above the common minimum inhibitory concentrations for Staphylococcus up to three months post-operatively. . Conclusion. This study provides the first pharmacokinetic description of the local application of vancomycin with CaSO. 4. as a carrier, documenting slow release, systemic safety and a release profile far more interesting than from PMMA. In particular, considering in vitro data, concentrations of vancomycin active against staphylococcal biofilm were seen for several weeks. Cite this article: Bone Joint J 2017;99-B:1537–44

Aim. The use of bone substitutes such as calcium sulfate (CaSO4) and hydroxyapatite with local antibiotics are crucial in the treatment of osteomyelitis. They allow the treatment of the dead space and locally provide large concentrations of antibiotics. However, it is unknown whether use of local vancomycin may elute and influence on vancomycin plasma levels. The aim of this study is to assess whether the addition of vancomycin to CaSO4 with hydroxyapatite may increase vancomycin plasma concentrations in in patients with osteomyelitis and therefore alter dosage adjustments. Method. The present study investigates the vancomycin plasma concentrations at 72–94 h post-surgery after the application of local vancomycin within CaSO4 (660mg vancomycin/10cc) and hydroxyapatite bone substitute in patients treated with empiric intravenous vancomycin and surgically treated for osteomyelitis. Vancomycin plasma concentrations were analyzed in twelve patients with osteomyelitis surgically treated with local release of vancomycin by CaSO4 and hydroxyapatite and undergoing therapeutic drug monitoring (TDM) of their vancomycin plasma concentrations as it is routinely done in our hospital. From 2019 to 2022, demographic data, microbiology, type of osteomyelitis, amount of local vancomycin applied, alteration of renal function, and vancomycin levels were retrospectively analyzed. Results. Twelve patients were included: 9(75%) were men. Median (range) demographic and clinical data: age: 51(26–67) years; body mass index: 27.7(18–46.4) kg/m2;baseline serum creatinine: 0.85 (0.7–1.24)mg/dl and 5(41.7%) with and glomerular filtration rate < 90ml/min(CPD-EPI, ml/min). Most frequently isolated microorganisms were Staphylococci (58%). Seven (54%) patients were classified as Cierny-Mader Osteomyelitis type III, 3(23%) as type IV and 2(23%) as type I. Treatment data: initial dose of vancomycin: 1g/8h in 9(75.0%) and 1g/12h in 3(25%) patients, total daily dose/body weight: 35.3(15.9–46.2) mg/kg. Pharmacokinetic data:days of iv vancomycin treatment until first TDM measurement: 3(3–4) days; minimum and maximum vancomycin plasma concentrations: 9.4(3–17.3) mg/L and 19.6(11.3–33.4) mg/L, respectively; patients with therapeutic concentrations: 6(50%); infratherapeutic: 4(33.3%) and supratherapeutic/potentially toxic: 2(16.7%). These 2 patients were young, had a baseline conserved renal function and were receiving the higher dose of 1g/8h. Conclusions. Vancomycin incorporated into the bone substitute appears not to increase blood concentrations of the glycopeptide in patients with osteomyelitis treated surgically and with intravenous vancomycin. However, 2 of the 12 patients presented supratherapeutic and potentially nephrotoxic vancomycin concentrations in the first TDM measurement, even though they were young and without renal impairment and needed and unexpected dose reduction. These results suggest the need to confirm the safety of local vancomycin in further larger clinical studies

Topically applied vancomycin powder has been used to decrease surgical site infection rates in spinal surgeries, however, randomized controlled trials in total joint arthroplasty are lacking. Application of vancomycin powder topically in the surgical site has theoretical benefit including high local concentration. In this study, we aimed to determine whether intra-operative topical antibiotics are safe and effective as IV antibiotics in preventing post-surgical site infections. The trial was a randomized controlled, double blind, non-inferiority study. All patients received pre-operative IV antibiotics (cefazolin or vancomycin) within 60 minutes of skin incision. The controlled group received two doses of post-operative IV antibiotics (two grams cefazolin or one gram vancomycin if cefazolin allergy). In the treatment group, the orthopaedic surgeon applied one gram vancomycin powder (500mg applied directly on the prosthesis and 500mg applied above the closed joint capsule). The incidence of acute surgical site infection was defined as positive deep cultures within 42 days of procedure. All patients with evidence of infection underwent joint aspiration for culture. After one year, 80 patients had received the topical vancomycin treatment and 85 patients had received the standard treatment. In the topical vancomycin group versus the controlled group, the average age was 64 vs 66, average BMI was 35.7 vs 33.4, number of males 33 vs 29, number of females 47 vs 56, and diabetic patients 16 vs 13. The number of infections in the topical vancomycin group was three vs zero in the post-operative IV antibiotic treatment group. One Tailed Z-test P Value = 0.03. This study statistically demonstrated inferiority of topical vancomycin in comparison to the use of IV antibiotics post-operatively in preventing deep wound infections in TKA. The authors would caution against the sole use of intra-operative vancomycin in TKA to prevent post-operative infection

Periprosthetic joint infection (PJI) occurs in 0.2-2% of primary hip and knee arthroplasty and is a leading cause of revision surgery, impaired function, and increased morbidity and mortality. Topical, intrawound vancomycin administration allows for high local drug concentrations at the surgical site and has demonstrated good results in prevention of surgical site infection after spinal surgery. It is a promising treatment to prevent infection following hip and knee arthroplasty. Prior studies have been limited by small sample sizes and the low incidence of PJI. This systematic review and meta-analysis was performed to determine the effectiveness of topical vancomycin for the primary prevention of PJI in hip and knee arthroplasty. A search of Embase, MEDLINE, and PubMed databases as of June 2020 was performed according to PRISMA guidelines. Studies comparing topical vancomycin to standard perioperative intravenous antibiotics in primary THA and TKA with a minimum of three months follow-up were identified. The results from applicable studies were meta-analysed to determine the impact of topical vancomycin on PJI rates as well as wound-related and overall complications. Results were expressed as odds ratios (ORs) and 95% confidence intervals. Nine comparative observational studies were eligible for inclusion. 3371 patients treated with 0.5-2g of topical vancomycin were compared to 2884 patients treated with standard care. Only one of nine studies found a significantly lower rate of PJI after primary THA or TKA (OR 0.09-1.97, p=0.04 for one study, p>0.05 for eight of nine studies), though meta-analysis showed a significant benefit, with vancomycin lowering PJI rates from 1.6% in controls to 0.7% in the experimental group (OR 0.47, p=0.02, Figure 1). Individually, only one of five studies showed a significant benefit to topical vancomycin in THA, while none of seven studies investigating PJI after TKA showed a benefit to topical vancomycin. In meta-analysis of our subgroups, there was a significant reduction in PJI with vancomycin in THA (OR 0.34, p=0.04), but there was no significant difference in PJI after TKA (OR 0.60, p = 0.13). In six studies which reported complication rates other than PJI, there were no significant differences in overall complication rates with vancomycin administration for any study individually (OR 0.48-0.94, p>0.05 for all studies), but meta-analysis found a significant difference in complications, with a 6.7% overall complication rate in controls compared to 4.8% after topical vancomycin, largely driven by a lower PJI incidence (OR 0.76, p=0.04). Topical vancomycin is protective against PJI after hip and knee arthroplasty. No increase in wound-related or overall complication rates was found with topical vancomycin. This meta-analysis is the largest to date and includes multiple recent comparative studies while excluding other confounding interventions (such as povidone-iodine irrigation). However, included studies were predominantly retrospective and no randomized-controlled trials have been published. The limited evidence summarized here indicates topical vancomycin may be a promising modality to decrease PJI, but there is insufficient evidence to conclusively show a decrease in PJI or to demonstrate safety. A prospective, randomized-controlled trial is ongoing to better answer this question. For any figures or tables, please contact the authors directly

While pre-soaking grafts in vancomycin has demonstrated to be effective in observational studies for anterior cruciate ligament reconstruction (ACLR) infection prevention, the economic benefit of the technique is uncertain. The primary aim of this study was to determine the cost-effectiveness of vancomycin pre-soaking during primary ACLR to prevent post-operative joint infections. The secondary aims of the study were to establish the breakeven cost-effectiveness threshold of the technique. A Markov model was used to determine cost effectiveness and the incremental cost effectiveness ratio of additional vancomycin pre-soaking compared to intravenous antibiotic prophylaxis alone. A repeated meta-analysis of nine cohort studies (Level III evidence) was completed to determine the odds ratio of infection with vancomycin pre-soaking compared to intravenous antibiotics alone. Estimated costs and transitional probabilities for further surgery were obtained from the literature. Breakeven threshold analysis was performed. The vancomycin soaking technique provides an expected cost saving of $600AUD per patient. There was an improvement in the quality-adjusted life years of 0.007 compared to intravenous antibiotic prophylaxis alone (4.297 versus 4.290). If the infection rate is below 0.023% with intravenous antibiotics alone or the additional intervention cost more than $1000AUD, the vancomycin wrap would no longer be cost-effective. For $30AUD, the vancomycin soaking technique provides a $600AUD cost saving by both reducing the risk of ACLR related infection and economic burden of infection. Treating septic arthritis represents a mean cost per patient of 6 times compared to that of the primary surgery. There has been no previous cost-effectiveness study of the vancomycin wrap technique. The vancomycin pre-soaking technique is a highly cost-effective method to prevent post-operative septic arthritis following primary ACLR

Aim. Vancomycin is frequently used for bone and joint infections (BJI) because of the main role of Gram-positive bacteria as potential causal agents. It is crucial to achieve optimal vancomycin plasma concentrations since the first day to maximize treatment clinical and microbiological efficacy. The aim was to describe the patients’ profile that are more likely to achieve an optimal pharmacokinetic/pharmacodynamics (PK/PD) vancomycin target in the first therapeutic drug monitoring (TDM) sample. Methods. Retrospective study (March 2018-January 2022) in a university hospital including all patients treated with vancomycin for a BJI and undergoing TDM. Initial dose (1g/8-12h) was selected by the responsible clinician. Vancomycin plasma concentrations were obtained pre-dose (Cmin,ss) and 60-minutes after the infusion on day 2 of treatment. Global exposure measured by the area under the curve of plasma concentrations during 24h (AUC024h) was estimated using a bicompartmental PK model. An AUC024h/CMI=400–600mg*h/L was considered optimal, <400 infratherapeutic and >600 supratherapeutic, based on recent guidelines, and patients were classified into these 3 groups. A value of CMI=1 mg/L was considered, following guidelines recommendations. Categorial data: percentages and quantitative data as mean (standard deviation). Results. Ninety-five patients were included: 22(23.2%), 43(45.3%) and 30(31.6%) presented an infratherapeutic, optimal and supratherapeutic PKPD target, respectively. Medium age was 75,8(13,5) in the supratherapeutic group versus 57,2(16,3) in the infratherapeutic group. Weight (kg) was higher in the infratherapeutic group 80,8(18,4) versus 66,8(15,5) in the supratherapeutic group. Vancomycin dose (mg/kg/d) was 43,5(12,4) in the supratherapeutic group versus 34,5(10,8) in the infratherapeutic group. There were 17(56,7) patients who received 1g/8h of vancomycin in the supratherapeutic group and 6 (27,3) in the infratherapeutic group. Baseline glomerular filtration rate (BGF (CKD-EPI) (mL/min/1.73m2) was 71,5(20,1) in the supratherapeutic group and 100,0 (19,9) in the infratherapeutic group. The AUC24h/CMI was 788,0(186,1) in the supratherapeutic group and 323,7(55,4) in the infratherapeutic group. Significant differences observed in age, body weight (BW), baseline renal function and dose/frequency of vancomycin. Dosage adjustments recommendations were made in 62(65.3%) patients: 31(32.6%) dose-increase, 29(30.5%) reduction and 2 cases (2.1%) a temporary suspension. Conclusions. Less than 50% of patients achieved an optimal exposure of vancomycin on day 2 of treatment. Patients with infratherapeutic levels had a younger age and a higher body weight and glomerular filtration rate. In addition, they had received a lower vancomycin initial dose. On the contrary, a potentially toxic exposure was observed within older patients with impaired baseline renal function. These data suggest the relevance of an early vancomycin TDM for optimizing the treatment of BJI

The routine use of intraoperative vancomycin powder to prevent postoperative wound infections has not been borne out in the literature in the pediatric spine population. The goal of this study is to determine the impact of vancomycin powder on postoperative wound infection rates and determine its potential impact on microbiology. A retrospective analysis of the Harms Study Group database of 1269 adolescent idiopathic scoliosis patients was performed. Patients that underwent a posterior fusion from 2004-2018 were analyzed. A comparative analysis of postoperative infection rates was done between patients that received vancomycin powder to those who did not. Statistical significance was determined using Chi-squared test. Additionally, the microbiology of infected patients was examined. In total, 765 patients in the vancomycin group (VG) were compared to 504 patients in the non-vancomycin group (NVG). NVG had a significantly higher rate of deep wound infection (p<0.0001) and associated reoperation rate compared to VG (p<0.0001). Both groups were compared for age, gender, race, weight, surgical time, blood loss, number of levels instrumented, and preop curve magnitude. There were significant differences between the groups for race (p<0.0001); surgical time (p=0.0033), and blood loss (p=0.0021). In terms of microbiology, VG grew p.acnes (n=2), and serratia (n=1), whereas NVG grew p.acnes (n=1) and gram positive bacilli (n=1). The remaining cultures were negative. The use of intraoperative vancomycin powder in adolescent idiopathic scoliosis appears to contribute significantly to deep wound infection prevention and reduction of associated reoperations. Based on this study's limited culture data, Vancomycin does not seem to alter the microbiology of deep wound infections

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)

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. Local antibiotics, delivered to the site of infection, achieve high tissue concentrations and are used as an adjunct to systemic therapy. Local gentamicin provides levels well above the minimum inhibitory concentration and may be sufficient on its own, however, the efficacy of single or combination local antibiotics has not been studied. This retrospective study evaluated the effect of combination aminoglycoside and vancomycin local antibiotic treatment compared to aminoglycoside alone in the surgical management of bone infection. Method. We studied patients with microbiologically confirmed osteomyelitis and fracture-related infection, who had implantation of antibiotic carriers as part of their surgical management. Data including patient demographics, type of surgery, microbiological characteristics, BACH score, duration of antibiotic treatment and clinical outcomes were collected. Failure of therapy was a composite of recurrence of infection, continued or new antimicrobial therapy, or reoperation with suspected or confirmed infection at one year after index surgery. Results. There were 266 patients who met the inclusion criteria. Nine patients died before the outcome endpoint at 12 months and five patients were lost to follow up so were excluded. 252 patients were included in the final analysis and were well matched with regard to demographics, BACH score and microbiology. 113 patients had treatment with aminoglycoside alone and 139 patients had combination aminoglycoside and vancomycin. There was no difference in the failure rate between groups; 10/113 (8.8%) in the aminoglycoside alone and 12/139 (8.6%) in the combination group, p = 0.934. There was no difference for reoperation, ongoing suppressive antibiotic use, or clinical suspicion of infection. Multivariate analysis showed that there was no added benefit of combination therapy (OR 1.54: 95%CI 0.59-4.04, p=0.38). BACH score and low BMI were associated with increased risk of failure (BACH OR 3.49: 95%CI 1.13-10.76, p=0.03; Low BMI OR 0.91: 95%CI 0.84-0.99, p-0.037). The form of the carrier material (pellets or injectable paste) had no effect on failure rate (p=0.434). Aminoglycoside resistance (confirmed and presumed) occurred in 39/113 (34.5%) of the aminoglycoside only group and 36/139 (25.9%) of the combination group (p=0.137). The presence of aminoglycoside resistance had no effect on failure rate (OR 0.39: 95%CI 0.05-3.01, p=0.37). Conclusions. Clinical outcome was not improved by the addition of vancomycin to aminoglycoside alone as local therapy for the management of osteomyelitis and FRI. Laboratory measured resistance, using currently accepted breakpoints, may not be relevant in local therapy

Background. Systemically administered vancomycin may provide insufficient target-site concentrations. Intraosseous vancomycin administration has the potential to overcome this concern by providing high target-site concentrations. Aim. To evaluate the local bone and tissue concentrations following tibial intraosseous vancomycin administration in a porcine model. Method. Eight female pigs were assigned to receive 500 mg diluted vancomycin (50 mg/mL) through an intraosseous cannula into the proximal tibial cancellous bone. Microdialysis was applied for sampling of vancomycin concentrations in tibial cancellous bone adjacent to the intraosseous cannula, in cortical bone, in the intramedullary canal of the diaphysis, in the synovial fluid of the knee joint, and in the subcutaneous tissue. Plasma samples were obtained. Samples were collected for 12 hours. Results. High vancomycin concentrations were found in the tibial cancellous bone with a mean peak drug concentration of 1,236 (range 28–5,295) µg/mL, which remained high throughout the sampling period with a mean end concentration of 278 (range 2.7–1,362.7) µg/mL after 690 min. The mean (standard derivation (SD)) peak drug concentration in plasma was 19 (2) µg/mL, which was obtained immediately after administration. For the intramedullary canal, in the synovial fluid of the knee joint, and subcutaneous tissue, comparable mean peak drug concentration and mean time to peak drug concentration were found in the range of 7.5–8.2 µg/mL and 45–70 min, respectively. Conclusions. Tibial intraosseous administration of vancomycin provided high mean concentrations in tibial cancellous bone throughout a 12-hour period, but with an immediate and high systemic absorption. The concentrations in cancellous bone had an unpredictable and wide range of peak concentration. Low mean concentrations were found in all the remaining compartments. Our findings suggest that intraosseous vancomycin administration in proximal tibial cancellous bone only is relevant as treatment in cases requiring high local concentrations nearby the intraosseous cannula

Aim. The management of PJIs is slowed down by the presence of bacteria forming biofilms where they may withstand antibiotic therapy. The use of adjuvant strategies, such as hydrolytic enzymes cocktail targeting biofilm matrices and facilitating their dispersion, is a promising option to limit impact of biofilms. Our aim was to evaluate the effect of enzymes cocktail combined with antibiotic dual therapy of rifampicin and vancomycin in a relevant in-vitro model. Method. Mature methicillin-resistant Staphylococcus aureus biofilms were grown on Ti-6Al-4V coupons by adding 1mL of a 8Log10 ATCC 33591 suspension in TGN (TSB + 1% glucose + 2% NaCl) to 24-wells plates containing the coupons and incubating the plates for 24h at 37°C with a continuous 50rpm agitation. The samples were rinsed and placed in 6 wells plates containing 1ml of the enzymatic cocktail (C.D.D.) solution (tris-buffered (pH 7.0) solution of 400 U/ml of aspecific DNA/RNA endonuclease, 50 U/ml of endo-1,4-b-D-glucanase, and 0.06 U/ml of β-N-acetylhexosaminidase). 9ml of TGN or TGN containing antibiotics RIF/VAN (rifampicin 5µg/mL + vancomycin 8µg/mL) at clinically relevant concentrations found locally in bone or joints, was then added and the samples were incubated in identical conditions for 24h. The samples were then recovered and rinsed. CFU counts were obtained by recovering the bacteria with sonication, serial dilutions, and TSA plating. Biomass was determined via crystal violet staining, followed by dye solubilization in acetic acid, and absorbance measurement using a spectrophotometer. Results. Significant reductions in bacterial counts were observed in biofilms exposed to either RIF/VAN or RIF/VAN+CDD, by respectively 2,6 and 3,7Log10 when compared to samples reincubated with TGN alone (p <0.05). Additionally, CFU counts in samples exposed to RIF/VAN+CDD were reduced by 1,1Log10 when compared to those exposed to RIF/VAN (p<0,05). Significant reduction in biomass (-29,8%, p<0.05) was observed for coupons exposed to RIF/VAN+CDD when compared to C.D.D alone (figure 1). Conclusions. The concurrent utilization of enzymes with rifampicin and vancomycin, holds promise as a feasible method to address periprosthetic joint infections (PJIs). For any tables or figures, please contact the authors directly

Abstract. Background. The aim of the present experimental study was to analyse vancomycin elution kinetics of nine bone fillers used in orthopaedic and trauma surgery over 42 consecutive days. Methods. Two allograft bone chips (carriers 1 and 2), a calcium-sulfate matrix (carrier 3), a hydroxyapatite/calcium-sulphate composite (carrier 4), four bone cements (carriers 5-8) and a pure tricalcium phosphate matrix (carrier 9), either already contained vancomycin, or were mixed with it following manufacturer's recommendations. Over 42 days, half of elution medium was substituted by the same amount of PBS at 9 distinct time points. Vancomycin concentration in obtained samples were measured with a kinetic microparticle immunoassay, and masses consecutively calculated. To enhance comparability between carriers analysed, vancomycin mass released related to overall mass within each probe was determined. Notably, elution kinetics of carriers 1 to 4 have been published previously. Results. All carriers initially released high vancomycin masses, followed by constant reduction later into the experiment. Mean initial vancomycin masses released after 4 hours were highest for carriers 1 (337.7 ± 76.2 mg), 9 (68.4 ± 4.9 mg), and 2 (49.0 ± 54.6 mg). From prefinal (35 days) to last measurement (42 days) carriers 2 (8.6 ± 4.8 mg), 1 (2.4 ± 1.0 mg), and 5 (0.1 ± 0.1 mg) had released highest vancomycin masses. Notably, all five bone cements tested only released a small percental amount of their total mass up to the last measurement (42 days; 2.1% – 9.3%), whilst allografts and resorbable synthetic bone fillers discarded high percental values (22.5% – 79.2%). Conclusions. Elution kinetics differ between 9 antibiotic-loaded bone fillers, with high vancomycin masses released by allografts and resorbable bone fillers over time. Transferred to clinical practice, these may be favoured over bone cements in case prolonged and high antibiotic release is warranted rather than mechanical stability

Aim. Prompt and sufficient broad spectrum empirical antibiotic treatment is key to prevent infection following open tibial fractures. Succeeding co-administration, we dynamically assessed the time for which vancomycin and meropenem concentrations were above relevant epidemiological cut-off minimal inhibitory concentrations (T>MIC) in tibial compartments for the bacteria most frequently encountered in open fractures. Low and high MIC-targets were applied: 1 and 4 µg/mL for vancomycin and 0.125 and 2 µg/mL for meropenem. Materials and methods. 8 pigs received a single dose of 1000 mg vancomycin and 1000 mg meropenem simultaneously over 100 min and 10 min, respectively. Microdialysis catheters were placed for sampling over 8 h in tibial cancellous bone, cortical bone, and adjacent subcutaneous adipose tissue. Venous blood samples were collected as references. Results. Across the targeted epidemiological cut-off values, vancomycin displayed longer T>MIC in all the investigated compartments in comparison to meropenem. For both drugs, cortical bone exhibited the shortest T>MIC. For the low MIC targets and across compartments, T>MIC ranged between 208–499 min (46–100%) for vancomycin and 189–406 min (42–90%) for meropenem. For the high MIC targets, T>MIC ranged between 30–446 min (7–99%) for vancomycin and 45–181 min (10–40%) for meropenem. Conclusion. The differences in the T>MIC between the low and high targets illustrates how the interpretation of these results is highly susceptible to the defined MIC target. To encompass any trauma, contaminating or individual tissue differences, a more aggressive dosing approach may be considered to achieve longer T>MIC in all the exposed tissues and thereby lowering the risk of acquiring an infection after open tibial fractures

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. The incidence of orthopaedic methicillin-resistant staphylococcus aureus infections is increasing. Vancomycin may therefore play an increasingly important role in orthopaedic perioperative antimicrobial prophylaxis. Adequate antimicrobial concentrations at target site is essential for prevention of orthopaedic infections. Current studies investigating perioperative bone and soft tissue concentrations of vancomycin are sparse and challenged by a lack of appropriate methods. The aim of this study was therefore to assess the concentration of vancomycin in plasma, subcutaneous tissue and bone after single dose administration using microdialysis (MD) in patients undergoing total knee replacement. Method. 1,000 mg of vancomycin was postoperatively administered intravenously over 100 minutes to 10 male patients undergoing primary total knee replacement. Vancomycin concentrations in plasma, subcutaneous tissue (SCT), cancellous and cortical bone were measured the following 8 hours. MD was applied for sampling in solid tissues. The vancomycin concentration in MD-samples was determined using ultra-high performance liquid chromatography, whilst the free plasma concentration was determined using a chemistry analyzer*. Results. For all extravascular tissue, an impaired penetration was demonstrated, with lower area under the concentration-time curve (AUC) compared to free plasma. The lowest AUC was found in cortical bone. For all tissues, tissue penetration expressed as the ratio of the area under the concentration–time curve from 0 to the last measured value (AUC0-last tissue/AUC0-last plasma) were below 0.5. The time to a mean clinically relevant minimal inhibitory concentration (MIC) of 2 mg/L were 3, 36, 27 and 110 min for plasma, SCT, cancellous and cortical bone, respectively. As opposed to the other compartments, a mean MIC of 4 mg/L was not reached in cortical bone. The AUC0-last and peak drug concentrations (Cmax) for SCT, cancellous and cortical bone were lower than those of free plasma. The time to Cmax was higher for all tissues compared with free plasma. Conclusions. Penetration of vancomycin to bone and SCT was found to be impaired and delayed in male patients undergoing total knee replacement surgery. Adequate perioperative vancomycin concentrations may not be reached at target site using standard prophylactic dosage. *Cobas c501

Aims. Vancomycin may be an important drug for intravenous perioperative antimicrobial prophylaxis in spine surgery. We assessed single-dose vancomycin intervertebral disc, vertebral cancellous bone, and subcutaneous adipose tissue concentrations using microdialysis in a pig model. Methods. 8 female pigs received 1,000 mg of vancomycin intravenously as a single dose over 100 minutes. Microdialysis probes were placed in the C3-C4 intervertebral disc, C3 vertebral cancellous bone, and subcutaneous adipose tissue, and vancomycin concentrations were obtained over 8 hours. Venous blood samples were obtained as reference. Results. Ranging from 0.24 to 0.60, vancomycin 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. The lowest penetration was found in the intervertebral disc. The time to a mean clinically relevant minimal inhibitory concentration (MIC) of 4 μg/mL were 3, 17, 25, and 156 min for plasma, subcutaneous adipose tissue, vertebral cancellous bone and the intervertebral disc, respectively. In contrast to the other compartments, a mean MIC of 8 μg/mL was not reached in the intervertebral disc. An approximately 3-time longer elimination rate was observed in the intervertebral disc in comparison to all the other compartments (p < 0.001), and the time to peak drug concentration was higher for all tissues compared with plasma. Conclusions. Preoperative administration of 1,000 mg of vancomycin may provide adequate vancomycin tissue concentrations with a considerable delay, though tissue penetration was incomplete. However, in order also to achieve adequate intervertebral disc concentrations in all individuals and accommodating a potentially higher MIC target, supplemental application of vancomycin may be necessary

The use of antibiotic-loaded cement has become a well-accepted method to develop high local antibiotic concentrations in orthopedic surgery. A new surgical technique has been established in our department in order to further increase the local antibiotic concentration, when implanting a prosthesis during revision surgery. By additional superficial vancomycin coating of the bone cement, high local antibiotic concentrations are generated. They should reach inhibiting and bactericidal concentrations of the respective pathogen during the first days after surgery. The aim of this study was to state the safety of this method by analyzing postoperative serum and drain vancomycin concentrations. Attention was focused on possible systemic side effects. To determine nephrotoxicity, creatinine levels were also measured. In total 32 revision operations (hip n=10, knee n=22) with additional superficial vancomycin coating were performed between 05/2013 and 04/2015. Procedures with removal of the prosthesis following temporary spacer implantation were excluded. In nine cases a one-stage procedure was performed, while in the others an arthroplasty or arthrodesis was performed after temporary spacer explantation. Vancomycin powder (2 grams) was added superficially to the surface of the bone cement and pressed onto manually before curing. Postoperative Vancomycin levels were measured in serum and the drain on day 1 to 5 or until the drain has been removed. In total 90 blood serum samples and 100 drain fluid samples were obtained. The highest median vancomycin level from the drain was documented on postoperative day 1 with a value of 555.3 μg/mL (range 66.1 – 1081.8), continually decreasing until postoperative day 4. The highest value was documented on the second postoperative day with 2170.0 μg/mL. On the first postoperative day, a median serum vancomycin level of 3.35 μg/mL was present (range <2.0 – 8.5), while from postoperative day 2 to 5 a median level less than 2.0 μg/mL (range <2.0 – 7.2) was documented. Anaphylactic reaction, red man syndrome or fever and chills were not observed after the surgical procedure. Furthermore, no subjective hearing loss was reported. Only in one case, a creatinine increase of 0.5 mg/dL from baseline value was detected. In this case the patient suffered preoperatively from a chronic kidney insufficiency. In total two reinfections occurred, one after explanting a spacer with subsequent hip total endoprosthesis, the other one after a one-stage hip revision. Superficial Vancomycin Coating of bone cement in orthopedic revision surgery represents a safe method to increase local inhibiting vancomycin concentrations

Aim. Determine the time concentration profile required to achieve vancomycin-mediated eradication of Staphylococcus aureus biofilm. This is critical for the identification of performance targets for local antibiotic delivery, yet has not been described. Method. Mature S. aureus UAMS-1 biofilms were grown on titanium-aluminum-niobium discs in Mueller Hinton broth (MHB). After 7 days, the discs were incubated in MHB containing vancomycin at 100, 200, 500, 1′000 and 2′000 mg/L. Both static and shaking conditions were tested. Samples were retrieved at intervals for up to 28 days for quantification of residual biofilm by sonication and serial dilution plating. One additional disc was processed per time point for scanning electron microscopy. Results. Progressive and significant reduction of viable bacteria was observed over time at all vancomycin concentrations in both static and shaking conditions. After 28 days under static conditions, the S. aureus biofilm was completely eradicated at 200 mg/L vancomycin and higher concentrations. Biofilm could could however not be eradicated under shaking conditions at any concentration. Logistic regression documents time of exposure at ≥200 mg/L as being the essential determinant of eradication. Conclusions. The clinical relevance of the present study is that it is not impossible to eradicate mature S. aureus biofilm from metal implants by vancomycin alone, fostering efforts to optimize local delivery. The required time concentration profile cannot be achieved yet by systemic administration or any of the local delivery vehicles available. Even longer exposure as 28 days might be required as wound fluid flow might influence unfavourably biofilm resistance to vancomycin

We wanted to study the risk of systemic toxic effect of gentamycin/vancomycin loaded spacers, and to investigate whether there is any difference in the elution of gentamycin and vancomycin to the joint fluid between theatre- made and in factory ready-made spacers. The study consists of 28 patients. In group one, 14 patients were given a in factory ready-made spacer containing gentamycin 1,1g – 3,2g and vancomycin 1,1g – 3,2g depending of the size of the spacer. In group two, 14 patients were given spacers made in the operating theatre. from PMMA containing 0,5 g gentamycin in each 40 g batch. 4 g vancomycin were added to each batch of 40 g PMMA. The concentration of gentamycin and vancomycin was measured from drainfluid and in serum day 1 and 2 after the operation. Group one Group two Significance. Vancomycin drain day 1 10,3 (2,0–23.3) 88,5 (11,7–242,9) p<0,001. Vancomycin drain day 2 6,3 (2,0–17,5) 55,2 (7,5–161,0) p<0,001. Vancomycin serum day 1 2,0 (2,0–2,0) 1,8 (0,7–2.0) ns. Vancomycin serum day 2 2,0 (1,6–2,2) 1,9 (1,0–2,0) ns. Gentamycin drain day 1 23,4 (0,5–68,0) 44,3 (11,0–117,5) p=0,05. Gentamycin drain day 2 8,7 (0,8–16,1) 18,0 (6,8–45,3) p<0,005. Gentamycin serum day 1 0,2 (0,2–0,2) 0,3 (0,2–1,3) ns. Gentamycin serum day 2 0,2 (0,0–0,2) 0,3 (0,2–1,1) ns. In theatre-made spacers had a significant higher concentration of both gentamycin and vancomycin in the joint fluid. Even with very high consentrations of gentamycin and vancomycin in the joint fluid the concentrations in serum were far below the toxic limit and no toxic reactions were observed. Gentamycin and vancomycin added to the hip spacers only to a very small degree passes to the circulation system. In theatre-made spacers have a significantly higher elution of gentamycin and vancomycin than in factory ready-made spacers. If a high initial concentration of gentamycin and vancomycin in joint fluid is desired. in theatre-made spacers should be considered