Aim. To evaluate clinical outcomes for patients with osteomyelitis at a major trauma centre limb reconstruction unit. Method. We prospectively evaluated 137 patients on the limb reconstruction database with long bone osteomyelitis. Data on initial diagnosis, management (bone resection, use of external fixation, dead space and soft tissue management), microbiology and 2-year outcomes were collated. 11 patients' data was incomplete and 9 underwent primary amputations; these were excluded from microbiology data analysis. The patient data was categorised into microbiological culture negative or culture positive groups. Inter-group comparisons were made to evaluate two-year outcomes and percentage failure rate. Results. Forty percent (55/137) of patients presented with infected non-union, 20% (27/137) infected fractures, 19% (26/137) chronic osteomyelitis without implants and 14% (19/137) had infected metalwork. Removal of metalwork, reaming and debridement were the most frequently performed procedures, often in combination. 3% of patients failed treatment and had persistent infected non-union. The most common microorganisms identified in the culture positive group were Staphylococcus aureus (47.6%), Coagulase Negative Staphylococcus species (11.9%) and Enterobacter cloacae (11.9%), however multiple organism growth was more common than single organism growth, 53% and 47% respectively. 8% of culture negative patients had histological evidence of infection on biopsy. Conclusions. The 2-year failure rate (persistent infective non-union) was higher in the culture negative group (8%) than the culture positive group (1%). The higher failure rate may be secondary to lack of organisms isolated and available sensitivities from deep tissue samples. In 9 cases patient preference led to primary amputation over limb salvage procedures, without further infection. Our work highlights the array of factors contributing to outcome in this patient group. The incidence of micro-organisms commonly encountered in this cohort will provide further evidence to support choice of antibiotic for empirical therapy especially in cases which are culture negative. Finally, there are many challenges in achieving adequate outcomes in patients with long bone infections thus the need for a multidisciplinary team approach in this patient cohort is invaluable. Routine histology testing may be beneficial as this may highlight infective processes in culture negative patents thereby allowing optimization of patient management

Aims. The microbiological detection of microorganisms plays a crucial role in the diagnosis as well as in the targeted systemic and local antibiotic therapy of periprosthetic infections (PJI). Despite extensive efforts to improve the sensitivity of current culture methods, the rate of culture-negative infections is approximately 10–20% of all PJI. This study investigates an preanalytical algorithm (culture collection and direct processing in the OR) to potentially increasing culture yield in patients with PJI. Methods. Patients undergoing staged revision arthroplasty for PJI in our hospital between October 2021 and 2022 were included in this prospective pilot study. Intraoperatively twenty tissue samples were collected and distributed among 4 groups. Tissue samples were prepared according to standard without medium and in thioglycolate medium at 3 different temperatures (room temperature, 4°C, 37° for 24h before transport to microbiology) directly in the OR. The removed implants were sonicated. Cultures were investigated on days 1, 3, 7, 12, 14 for possible growth. All grown organism, the number of positive samples and the time to positivity were recorded and compared. Results. 71 patients were included (age, gender). Compared to the standard procedure the thioglycolate broth at 37°C was significantly more often culture-negative (p=0.031). No significant differences in the frequency of culture-negative samples were detected in the other groups. 8.4% (6/71) patients were culture negative in the standard culture but positive in the thioglycolate samples. In contrast, 7% (5/71) were culture negative in the thioglycolate samples but had bacterial detection in the standard approach. In 4.7% (3/63) of the patients, only the sonication showed growth, whereas 25.4% (16/63) had no growth in sonication fluid but in one of the cultures. For S. caprae, there was a significantly different distribution (p=0.026) with more frequent detection in the group with thioglycolate at 37°C. The standard procedure (p=0.005) and sonication (p=0.023) showed a shorter time to positivity of the culture compared to the thioglycolate approach at 4°C. Conclusions. No general differences could be shown between the standard preparation and the thioglycolate preparation; in particular, storage at different temperatures does not seem to result in any difference. For individual cases (8% in this study), bacterial growth was detected in the thioglycolate group that would have been culture-negative otherwise. There might be organism dependent differences in growth in different media

Aim. The aim of this study was to investigate the clinical relevance of an isolated positive sonication fluid culture (SFC) in patients who underwent revision surgery of a prosthetic joint. We hypothesized that cases with a positive SFC have a higher rate of infection and prosthesis failure during follow-up compared to controls with a negative SFC. Method. This retrospective multicentre observational study was performed within the European Study Group of Implant-Associated Infections (ESGIAI). All patients who underwent revision surgery of a prosthetic joint between 2013 and 2019 and had a minimum follow-up of 1 year were included. Patients with positive tissue cultures or synovial fluid cultures were excluded from the study. Results. 95 cases (positive SFC) and 201 controls (negative SFC) were included. There was no difference in infection and prosthesis failure during follow-up between both groups. When solely analysing patients that were not treated with antibiotics, 16% of the cases had an infection during follow-up versus 5% of the controls (P 0.046). Conclusions. Withholding antimicrobial treatment in patients with an isolated positive SFC is associated with a higher reinfection rate. Antimicrobial treatment should be considered in isolated positive SFC, especially in case of high virulent pathogens

Aim. Septic arthritis is a painful infection of articular joints that is typically treated by irrigation & debridement along with antibiotic therapy. There is debate amongst the medical community whether antibiotic administration should be delayed until fluid cultures have been taken to improve culture yield. However, delaying antibiotics can also have negative consequences, including joint destruction and sepsis. Therefore, the purposes of this study were to determine: 1) whether delayed antibiotic treatment affects culture yield and prognosis and 2) if the culture yield of patients treated for septic arthritis differs for hip, knee, and shoulder based on timing of antibiotic administration. Method. A retrospective analysis was conducted on 111 patients with septic arthritis of the hip, knee, or shoulder admitted from 3/2016 to 11/2018. In patients with multiple septic joints, each joint was analyzed individually (n=122). Diagnosis was determined by the treatment of irrigation & debridement and/or a positive culture. Patients without all intervention times recorded or with periprosthetic joint infection were excluded. Demographics, laboratory tests, culture results, and intervention times were obtained through chart review. Patients were grouped based on antibiotic therapy timing: >24 hours prior to arthrocentesis (Group 1), between 24 hours and 1 hour prior (Group 2), and 1 hour prior to post-arthrocentesis (Group 3). Analysis was conducted using chi-squared tests. Results. The mean age of each group were similar: Group 1 (n=38) 55.7 years, Group 2 (n=20) 57.2 years, and Group 3 (n=64) 54.8 years. No difference was observed in culture sensitivity between groups (p=0.825) with 71.1% (27/38) positive cultures in Group 1, 75% (15/20) in Group 2, and 76.6% (49/64) in Group 3. Similarly, frequency of related readmissions within 90 days (p=0.863) did not significantly vary: 26.3% (10/38) in Group 1, 20% (4/20) in Group 2, and 25% (16/64) in Group 3. Additionally, there were no significant differences in culture sensitivity in the knee (p=0.618; Groups: 87.5%, 75%, 70.6%), shoulder (p=0.517; Groups: 77.8%, 66.7%, 90%), and hip (p=0.362; Groups: 61.9%, 80%, 80%). Conclusions. Culture sensitivities and rates of readmission were similar for all patients regardless of antibiotic administration timing. These results suggest that antibiotic administration should not be delayed in septic arthritis to improve culture yield. However, the data does not suggest that early antibiotic administration will result in better clinical outcomes by lowering readmission rates. Further research is needed to better determine the clinical benefits that early administration of antibiotics may have on patient outcomes

Aim. Septic arthritis (SA) is considered a medical emergency. The most common etiological agents are glucose consuming bacteria, so we evaluated the clinical utility of synovial fluid (SF) glucose levels and other biochemical parameters for supporting the diagnosis of the disease and their association with a positive bacteria culture and joint destruction. Methods. Adult patients with SA diagnose were enrolled prospectively between July 2018 and October 2019. As control group, adults with knee osteoarthritis, meniscus and/or knee ligaments lesions were enrolled. SF samples were obtained from the joints by arthrocentesis/arthrotomy. Microbiological analyses of SF were performed using Brucella broth blood culture flasks, samples were incubated at 37°C with 5% CO. 2. for 24 hours. Gram stain, chocolate and blood agar were used for the identification and growth of the bacteria. SF glucose levels, pH and leukocyte esterase were measured as biochemical parameters using a glucometer and colorimetric test strips. The Outerbridge classification was used for grading the osteochondral injury. Furthermore, blood samples were collected from patients and control subjects for determining glucose levels. Results. We included 8 subjects with knee ligaments lesions, 6 with meniscus lesions and 5 with osteoarthritis as control group, as well as 20 patients with SA diagnose. The mean age of the patients was 57.8 years with a 65% of male predominance. The most common affected joint was the knee (85%). SF culture was positive in 60% of the cases and the most common etiological agent was Staphylococcus aureus (58.3%). SF glucose levels from patients were lower than the controls (P=0.0018) and showed the lowest concentration in patients with a positive culture (P=0.0004). There was also a difference between blood and SF glucose concentration from the positive culture patients (P<0.0001). Leucocyte esterase presented the highest values in positive culture patients (P=<0.0001) and a more acidic pH was found compared to the control group (P<0.0001). Regarding the osteochondral injury, the lowest concentrations of SF glucose were found in patients with a higher grade in the classification (P = 0.0046). Conclusions. SF glucose and leukocyte esterase concentrations might be a quick and cheap useful parameter for the physician for distinguishing between bacterial infection and not infected joint. In addition, the lowest SF glucose levels might give information about the joint damage due to the disease

Aim. Microbial identification in the setting of periprosthetic joint infections (PJI) is crucial to tailor the best combination of surgical and medical treatment. Given the high cost, low sensitivity and slow results associated with traditional cultures, s synovial fluid antibody assay was developed. We asked whether antibody testing may be used as a proxy to traditional culture in the setting of PJI. Method. A retrospective study of patients who underwent revision total hip (THA) and knee (TKA) arthroplasty between January 2019 and January 2020 was performed. All patients were aspirated prior to revision surgery and antibody testing was performed. All patients had samples harvested for culture as per standard of care. Results of the two tests and their concordance when an organism was identified were compared. A frequency table was used and a McNemar test was used to compare the two methods. Results. 419 patients were included in this study. Antibody testing had a sensitivity and specificity of 21.9% and 92.5%, respectively, compared to traditional cultures. There were 78.1% of false negative and 7.5% of false positives (McNemar test p<0.001). Of the 12 patients who had positive results in both tests, 5 (41.7%) had discordant pathogens identified in each test. Conclusions. Synovial fluid antibody testing performed poorly when used as a substitute for cultures and may not be a clinically adequate surrogate despite lower cost and faster results. Not only was there a low sensitivity, but also a high rate of discordant organisms between the two tests when both were positive

Aim. Diagnosis of periprosthetic joint infection (PJI) presents a real challenge in some patients. Batteries of tests are available to reach this diagnosis. It is unknown if blood cultures have any role in diagnosis of PJI. The objective of this study was to evaluate whether blood cultures, taken in a group of patients with PJI, was useful in identifying the infecting pathogen. Methods. The institutional database was used to identify all patients treated at our institution between 2000 – 2015 for PJI according to the latest MSIS criteria. There were a total of 864 patients with mean age of 68 years. Synovial fluid sample and/or deep tissue samples were analyzed and cultured in all of these patients. In 371 (42.9%) patients with PJI, blood cultures were also taken. Statistical analyses were performed for correlation purposes. Results. In 246 (66.3%) patients in whom an organism was isolated from joint fluid, blood cultures were negative. 32 (8.6%) patients had both negative blood and synovial joint tissue culture. Of the 93 (25%) patients with positive blood cultures, 77 (82.7%) patients had identical organism in the joint and 16 (17.2%) had different organisms. Interestingly one infection that was fungal in nature showed no growth on tissue/fluid culture, yet a fungal organism was isolated in blood culture. Additionally, of the 93 patients with positive blood cultures, 57 (61.2%) had signs of systemic sepsis with leukocytosis and increased PMN/left shift. Within the 57 patients, 50 (87.7%) had identical blood and joint culture and 7 (12.2%) were from different culture organisms. 36 (38.7%) patients had subclinical infection with no signs of systemic sepsis. Discussion. Although this study does not advocate the routine use of blood culture for diagnosis of PJI, the finding that blood culture is successful in isolating the infecting organism as the joint in a handful of cases is compelling. Thus, the result of blood culture when performed should be considered as representative of the infecting organism in PJI cases

Aim. Aseptic loosening is the leading cause of revision of total hip arthroplasty (THA). It is well recognized that an occult infection is the underlying cause of some aseptic revisions. Intraoperative cultures are central to the diagnosis of prosthetic joint infection (PJI). However, the diagnostic and prognostic value of unexpected positive intraoperative cultures remains unclear. The aim was to study whether first-time aseptic revision of a total hip arthroplasty with unexpected bacterial growth in cultures of intraoperatively taken biopsies have an increased risk of secondary revision due to all causes and increased risk of PJI revision, specifically. Method. Cases reported as first-time aseptic loosening revisions to the Danish Hip Arthroplasty Register (DHR) performed during January 1. st. , 2010, to May 15. th. , 2016, were included. DHR data were merged with the Danish Microbiology Database, which contains data from all intraoperatively obtained cultures in Denmark. Included first-time revisions were grouped based on the number of positive cultures growing the same bacteria genus: ≥2, 1 and 0 cultures. Revisions were followed until secondary revision, death, or end of follow-up period after one year. Relative risk for secondary revision due to all causes and PJI was estimated. Results. We included 2,305 first-time aseptic revisions. Unexpected growth was found in 282 (12%) of which 170 (60%) cases showed growth of the same bacteria in only one culture. Coagulase-negative staphylococcus accounted for 121 (71%). Secondary revision was performed in 163 (7%) cases, with PJI being the indication for revision in 43 (26%) cases. The relative risk of secondary revision was significantly higher for cases of one positive culture growing the same bacteria compared to culture negative cases, both for revision due to all causes; 1.73 (95%CI 1.07; 2.80) and PJI exclusively; 2.63 (1.16; 5.96). Cases of 2 or more biopsies culturing the same bacteria had a relative risk of all cause revision of 1.52 (0.82; 2.80). Conclusions. First-time aseptic loosening THA revisions with unexpected growth in only one biopsy culture had an increased risk of secondary revision, both due to all causes and PJI. Our findings indicate that some cases of unexpected growth of bacteria should likely be regarded as clinically significant and not sample contamination, underlining the need for more awareness and better strategies when treating patients with unexpected positive intraoperative cultures. The improved diagnosis of occult PJI in clinically aseptic THA is of great importance for future care of this large and growing patient group

Aim. Current guidelines for the diagnosis of prosthetic joint infection (PJI) recommend collecting 4–5 independent tissue specimens, with isolation of indistinguishable organisms from two or more specimens. The same principle has been applied to other orthopaedic device-related infections (DRI) including fracture-related infections. However there are few published data validating this approach in DRI other than PJI. We evaluated the performance of different diagnostic cutoffs and varying numbers of tissue specimens for microbiological sampling in fracture-related infections. Method. We used standard protocols for tissue sample collection and laboratory processing, and a standard clinical definition of fracture-related infection. We explored how tissue culture sensitivity and specificity varied with the number of tissue specimens obtained; and with the number of specimens from which an identical isolate was required (diagnostic cutoff). To model the effect of the number of specimens taken we randomly sampled n specimens from those obtained at each procedure, excluding procedures from which less than n specimens were collected, and calculated sensitivity and specificity based on this sample. For each value of n we repeated this process 100 times to estimate the mean sensitivity and specificity for n specimens. Results. We analysed data for 246 cases of suspected fracture-related infection. 77 (31%) met the clinical definition of infection. A median of 4 independent tissue samples were obtained from each procedure (IQR 4–5). Culture sensitivity was highest and specificity lowest using a diagnostic cutoff of 1 specimen for isolation of an organism; specificity increased at the expense of sensitivity with diagnostic cutoffs of 2 or 3 specimens. Culture sensitivity increased as the number of tissue specimens obtained increased from 1 to 4. Although there was a corresponding decline in specificity with increasing numbers of tissue specimens obtained, this was negligible when a diagnostic cutoff of 2 or 3 specimens with identical organisms was used. Using a cutoff of 2 specimens with identical organisms, obtaining 4 specimens gave a sensitivity of 68% (55–78%) and a specificity of 95% (86–99%). Small numbers prevented meaningful analysis of the diagnostic performance of five or more specimens. Conclusions. These data are analogous to findings in prosthetic joint infections, and suggest similar principles may be applied to tissue sampling and culture interpretation in other orthopaedic DRI including fracture-related infection. A larger study is underway to evaluate the performance of greater numbers of tissue specimens

Aims. The purpose of this study was to evaluate the infection-free outcome of patients underwent revision of total joint arthroplasty (TJA) for presumed aseptic causes, with positive intra-operative cultures. Patients and Methods. A retrospective cohort study was assembled with 130 patients undergoing revision knee (21 cases) or hip arthroplasty (109 cases) for presumed aseptic causes. For all patients five to seven separate intra-operative cultures were obtained and prosthesis sonication was done. Patients were diagnosed with a previously unsuspected prosthetic joint infection (PJI) if two or more cultures were. positive or a positive prosthesis sonication. Data were reviewed for demographic details, preoperative laboratory results and culture results. The endpoint was infection-free implant survival at 24 months. Results. Patients with unsuspected PJI was 16 out of 130 (12,3%). Following revision surgery, the rate of infection-free implant survival in patients with an unsuspected PJI was 68,8% (95% confidence intervals (CI) 45,6 to 92) at two years compared. with 94,7% (95% CI 90,5 to 98,9) in patients without PJI (p = 0.001). Conclusion. Around 12% of positive cultures can be expected after TJA aseptic revision surgery; in these cases, the rate of infection-free implant survival is lower than in cases without PJI

Aim. Microbiological culture of intraoperative periprosthetic tissue samples (IPTS) is one of the main criteria in diagnosing prosthetic joint infections (PJI) as stated by different guidelines. The current techniques are labor-intensive, prone for contamination and show low sensitivity. The aim of this study was to evaluate the added value of beadmill processing of IPTS and culturing in blood culture bottles (BCBs) over the conventional method of standard agar and broth alone. Method. We conducted a single-center prospective study from May 2017 to January 2018 at the GZA Hospitals, a secondary care hospital (1012 beds) in Antwerp, Belgium. IPTS from patients undergoing revision arthroplasty were consecutively processed. Each IPTS was aseptically divided in two equal parts: one was processed by direct inoculation on agar and in broths (non-homogenized method); the other was transferred in a sterile vial with saline solution and glass beads (EOLabs), homogenized using a mechanic cell disruptor for 30s (Disruptor genie, Scientific Industries), 2mL of the suspension was inoculated in (an)aerobic BCBs, agar plates and broths (homogenized method). Agar plates were incubated for 4d; broths and BCBs in BacT/Alert (bioMerieux) for 14d. Micro-organisms were identified using MALDI-TOF MS (Bruker). Sensitivity (Se) and specificity (Sp) were calculated against the IDSA definition of PJI for different culture sets: non-homogenized and agar/broth; homogenized processing and agar/broth, agar/broth/BCB, agar/BCB. Ethics committee approved the study. Results. Overall, 122 IPTS from 32 episodes from 29 patients were included; 14 subjects met the IDSA PJI criteria. No difference (Se71.4%, Sp88.8%) was observed between the conventional method and the homogenized method for the agar and broth set. An increased sensitivity was observed for the homogenized method with addition of BCBs (Se85.7%) in contrast to agars and broths alone (Se71.4%). The homogenized method with BCBs and agar plates showed an excellent specificity and positive-predictive value, indicating the lower contamination risk and facilitating the microbiological diagnosis. Adding broths to this combination increases the false positivity rate (Sp94.4%). A false positivity rate of 15/122 IPTS was observed for broths alone, in contrast to 2/122 for BCBs alone. Also, one case (1/14) would have been missed when using the homogenized method with agars and broths alone. Conclusions. Beadmill processing of IPTS and culturing in BCBs is a sensitive and highly specific culture method for diagnosis of PJI. The superior specificity versus conventional methods minimizes false positive results, which frequently lead to erroneous clinical decisions. Furthermore, this makes semi-automated laboratory processing possible

We compared the use of broth culture medium for samples taken in theatre with the standard practice of placing tissue samples in universal containers. A total of 67 consecutive patients had standard multiple samples of deep tissue harvested at surgery and distributed equally in theatre either to standard universal containers or to broth culture medium. These samples were cultured by direct and enrichment methods. The addition of broth in theatre to standard practice led to an increase in sensitivity from 83% to 95% and an increase in negative predictive value from 77% to 91%. Placing tissue samples directly into broth in the operating theatre is a simple, inexpensive way to increase the sensitivity of cultures from infected patients, and does not appear to compromise the specificity of these cultures. Cite this article: Bone Joint J 2014;96-B:1566–70

Introduction. A timely isolation of the causative bacterial species is of paramount importance in the treatment of periprosthetic joint infection (PJI). Sonication of the explanted endoprosthesis and the microbiological culture of sonicate fluid (SFC) has been proven to increase the rate of bacterial isolations in comparison to the conventional microbiological methods. The cultivation of aspired synovial fluid in blood culture bottles (BCB) has been shown to yield a higher rate of bacterial isolations and produce a lower rate of contaminants than cultivation on conventional agar plates. The primary aim of this study was to investigate whether the inoculation of BCB with sonicate fluid leads to a higher rate of bacterial isolations than the culture on agar plates. Secondly, we wanted to investigate whether the utilization of BCB leads to an earlier identification of the causative bacterial species. To our knowledge this is the first study to investigate the effects of BCB use on SFC. Methods. We performed a retrospective analysis comparing the results of the two different culture methods. To detect slow growing species all microbiological cultures, regardless of the culture method, were incubated for 14 days. Results. Of the 206 patients included in our study 112 showed a positive bacterial isolation. 50 patients showed a positive bacterial growth in the intraoperative tissue cultures, 45 patients showed a positive bacterial isolation in the synovial aspiration and 104 patients showed a positive bacterial growth in the SFC. From these 45 positive isolations in synovial cultures 24 were achieved through agar plate culture and 37 were achieved through incubation in BCB. From the 104 patients with a positive bacterial isolation through SFC 51 were possible through agar plate cultures and 101 were achieved through incubation in BCB. The utilization of BCB also reduced the culture time for both the culture of synovial fluid as well as for SFC. On average the BCB produced a positive bacterial growth one day before the conventional agar plate cultures for synovial fluid and over one day earlier for sonicate fluid. Discussion and conclusion. When sonicate fluid is cultured in blood culture bottles it leads to both an increase in positive bacterial isolations and quicker bacterial growth than the culture on conventional agar plates

Aim. Negative-pressure wound therapy (NPWT) is often propagated as treatment option for fracture-related infection (FRI). After surgical debridement and repeated NPWT dressing changes, the wounds are often closed by free flaps. Sometimes even healing by secondary intention seems an alternative. Recently, concerns have been raised on the long-term use of NPWT as it could be related to bacterial overgrowth and possible re-infection. The purpose of this study was to conduct a retrospective evaluation of the influence of long-term NPWT on tissue culture results and outcome in FRI patients. Method. Between January 1. st. , 2015 and December 31st, 2018, a total of 852 patients were treated with NPWT for different indications on the Department of Trauma Surgery. Inclusion criteria for this study were patients with a closed fracture, stabilized with osteosynthetic fixation and complicated with a confirmed FRI according to the FRI consensus definition. Patients were included when they received at least three NPWT dressing changes in the operating room. Exclusion criteria were patients younger than 18 years, or the absence of cultures results from dressing changes. Results. During the study period 23 patients met the inclusion criteria. According to the tripartite classification of Willenegger and Roth, one patient had an early, 14 a delayed and 8 patients a late onset FRI. Overall, 139 NPWT dressing applications were performed, with an average amount of six per patient. In 14 patients (61%) and 57 dressing changes (41%), at least 2 tissue cultures showed the same pathogen or at least one, in case of highly virulent organisms (e.g. S. aureus) during a single dressing exchange. Coagulase-negative staphylococci were present in 33% of the cases, followed by Enterococcus spp. (21%), S. aureus (16%), non-fermentative gram negative bacilli (14%) and Enterobacteriaceae (7%). Furthermore, 17 exchanges showed polymicrobial growth. Five patients had repeatedly significant growth of the same pathogen despite adequate antimicrobial therapy, within this group one patient was immunocompromised. Conclusions. In a large amount of patients (61%), a significant number of positive culture results could be acquired, even in the presence of adequate local and systemic antimicrobial therapy. The clinical relevance of these results remains unclear. This said, it seems important to limit the duration of NPWT as prolonged treatment could increase bacterial overgrowth and possible (re-)infection. Therefore, a rapid definitive soft tissue coverage should be encouraged. Future larger prospective clinical trials are required

Collection of 4–5 independent peri-prosthetic tissue samples is recommended for microbiological diagnosis of prosthetic joint infections. Sonication of explanted prostheses has also been shown to increase microbiological yield in some centres. We compared sonication with standard tissue sampling for diagnosis of prosthetic joint and other orthopaedic device related infections. We used standard protocols for sample collection, tissue culture and sonication. Positive tissue culture was defined as isolation of a phenotypically indistinguishable organism from ≥2 samples; and positive sonication culture as isolation of an organism at ≥50 cfu/ml. We compared the diagnostic performance of each method against an established clinical definition of infection (Trampuz 2011), and against a composite clinical and microbiological definition of infection based on international consensus (Gehrke & Parvizi 2013). 350 specimens were received for sonication, including joint prostheses (160), exchangeable components (76), other orthopaedic hardware and cement (104), and bone (10). A median of 5 peri-prosthetic tissue samples were received from each procedure (IQR 4–5). Tissue culture was more sensitive than sonication for diagnosis of prosthetic joint and orthopaedic device related infection using both the clinical definition (66% versus 57%, McNemar's Χ2 test p=0.016) and the composite definition of infection (87% vs 66%, p<0.001). The combination of tissue culture and sonication provided optimum sensitivity: 73% (95% confidence interval 65–79%) against the clinical definition and 92% (86–96%) against the composite definition. Results were similar when analysis was confined to joint prostheses and exchangeable components; other orthopaedic hardware; and patients who had received antibiotics within 14 days prior to surgery. Tissue sampling appears to have higher sensitivity than sonication for diagnosis of prosthetic joint and orthopaedic device infection at our centre. This may reflect rigorous collection of multiple peri-prosthetic tissue samples. A combination of methods may offer optimal sensitivity, reflecting the anatomical and biological spectrum of prosthetic joint and other device related infections

Introduction. Pre-operative urine screening is accepted practice during pre-operative assessment in elective orthopaedic practice. There is no evidence surrounding the benefits, effects or clinical outcomes of such a practice. Methods. A series of 558 patients undergoing elective admission were recruited during pre-assessment for surgery and were screened for UTIs according to a pre-existing trust protocol. All patients had their urine dipstick tested and positive samples were sent for culture and microscopy. Patients with a positive urine culture were treated prior to surgery and were admitted to the elective centre where strict infection control methods were implemented. The patients were followed up after their surgery and divided into three clinical groups: uneventful surgery; Suspected wound infection; Confirmed wound infection. Results. 85% of dipsticks tested were positive, while only 7% of the urine samples were culture positive. Over 36% of patients with a pre-operative urinary tract infection showed some form of post-operative delayed wound healing or confirmed infection, versus 16% in the other sub-group, giving a relative risk of wound complications of 2:1. There was also an increase in confirmed infection in oozing wounds; 53% positive wound swabs versus 37% in those without a cultured urinary tract infection. A chi-squared analysis yielded a value of 6.07, giving a p value <0.02. There is therefore a statistically significant correlation between a positive urine culture and poor surgical outcome. Conclusion. Pre-operative urine screening and culture has a demonstrable correlation with post-operative surgical outcome. In the light of this study pre-operative urine culture should be mandatory for all pre-operative orthopaedic patients. It should be recognised that patients who present to pre-admission with a UTI are a high risk subgroup for wound infection post-operatively and this should be taken into account when consenting patients for surgery

In this study, a biomimetic triphasic scaffold was constructed to mimic the native cartilage-subchondral bone tissue structure. This scaffold contained chondral layer, calcified zone of cartilage (CZC) and subchondral bone layer. The chondral layer was type II collagen sponge, the CZC and the subchondral bone layer were derived from normal pig knee by decellularization. In order to build separate microenvironment for chondral layer and subchondral bone layer, a dual-chamber bioreactor was designed by computer aided design, manufactured by 3D printer using Poly Lactic Acid, with CZC as the barrier of these two chambers. Culture medium in these two chambers was circulated separately by peristaltic pumps. Amniotic mesenchymal stem cells were seeded in this scaffold, fluorescence labeling was used for cell tracking, total DNA content analysis was used to indicate cell proliferation, and inducing medium was used to direct stem cells differentiation. After 7 days culture, the cells regularly distributed in the scaffold, cell adhesion and proliferation was not affected. No cell migration across CZC occurred. Total DNA content analysis showed that cells in scaffold increased in a time-dependent manner. Chondrogenic and osteogenic medium could induce stem cells in these two chambers to differentiate into chondrocytes and osteocytes, respectively. Our pilot study showed that the dual-chamber culture system with biomimetic triphasic scaffold was feasible, therefore this system will be further modified and tested in vivo

Purpose. Disc degeneration is known to occur early in adult life, but at present there is no medical treatment to reverse or even retard the problem. Development of medical treatments is complicated by the lack of a validated long term organ culture model in which therapeutic candidates can be studied. The objective of this study was to optimize and validate an organ culture system for intact human intervertebral disc (IVD), which could be used subsequently to determine whether synthetic peptide growth factors can stimulate disc cell metabolism and initiate a repair response. Method. Seventy lumbar IVDs, from 14 individuals, were isolated within 24 h after death. Discs were prepared for organ culture by removing bony endplates but retaining cartilaginous endplates (CEP). Discs were cultured with no external load applied. The effects of glucose and FBS concentrations were evaluated. Dulbeccos Modified Eagle Media (DMEM) was supplemented with glucose, 4.5g/L or 1g/L, referred to as high and low (physiological) glucose, and FBS, 5% or 1%, referred to as high and low FBS, respectively. After a four week culture period, samples were taken across the disc using a 4 mm biopsy punch. Cell viability was analyzed using a live/dead fluorescence assay (Live/Dead, Invitrogen) and visualized by confocal microscopy. CEP discs were also placed in long term culture for four months, and cell viability was assessed. Western bolt analysis for the G1 domain of aggrecan was also performed to assess the effect of nutritional state on disc catabolism. Results. Cell viability in CEP isolated discs was evaluated after four weeks and four months of organ culture under high and physiological nutritional state. Previous studies have shown that high glucose levels are needed to maintain cell viability in organ culture, but in our model 96–98% live cells were present throughout the disc independent of FBS and glucose levels and the duration of culture tested. Western blot probing for the G1 domain of aggrecan showed no difference with the change of nutritional state across all regions indicating that low nutritional state had no detrimental effect on disc metabolism. Conclusion. We have developed a novel technique for isolation and culturing of intact IVDs. The described CEP system maintained sufficient nutrient supply and high cell survival in all regions of the disc for up to four months of culture also under physiological culturing condition. As the CEP system maintains high cell viability in long term cultures, it is a suitable model in which the regenerative effect of various bioactive peptides can be studied. The availability of an intact disc organ culture system has considerable advantage over the culture of isolated disc cells, as it maintains the cells in their unique microenvironment, so making any response to catabolic or anabolic agents more physiologically relevant

Purpose. Disc degeneration is known to occur early in adult life, but at present there is no medical treatment to reverse or even retard the problem. Development of medical treatments is complicated by the lack of a validated long term organ culture model in which therapeutic candidates can be studied. The objective of this study was to optimize and validate an organ culture system for intact human intervertebral disc (IVD), which could be used subsequently to determine whether synthetic peptide growth factors can stimulate disc cell metabolism and initiate a repair response. Method. Seventy lumbar IVDs, from 14 individuals, were isolated within 24 h after death. Discs were prepared for organ culture by removing bony endplates but retaining cartilaginous endplates (CEP). Discs were cultured with no external load applied. The effects of glucose and FBS concentrations were evaluated. Dulbeccos Modified Eagle Media (DMEM) was supplemented with glucose, 4.5g/L or 1g/L, referred to as high and low (physiological) glucose, and FBS, 5% or 1%, referred to as high and low FBS, respectively. After a four week culture period, samples were taken across the disc using a 4 mm biopsy punch. Cell viability was analyzed using a live/dead fluorescence assay (Live/Dead, Invitrogen) and visualized by confocal microscopy. CEP discs were also placed in long term culture for four months, and cell viability was assessed. Western bolt analysis for the G1 domain of aggrecan was also performed to assess the effect of nutritional state on disc catabolism. Results. Cell viability in CEP isolated discs was evaluated after four weeks and four months of organ culture under high and physiological nutritional state. Previous studies have shown that high glucose levels are needed to maintain cell viability in organ culture, but in our model 96–98% live cells were present throughout the disc independent of FBS and glucose levels and the duration of culture tested. Western blot probing for the G1 domain of aggrecan showed no difference with the change of nutritional state across all regions indicating that low nutritional state had no detrimental effect on disc metabolism. Conclusion. We have developed a novel technique for isolation and culturing of intact IVDs. The described CEP system maintained sufficient nutrient supply and high cell survival in all regions of the disc for up to four months of culture also under physiological culturing condition. As the CEP system maintains high cell viability in long term cultures, it is a suitable model in which the regenerative effect of various bioactive peptides can be studied. The availability of an intact disc organ culture system has considerable advantage over the culture of isolated disc cells, as it maintains the cells in their unique microenvironment, so making any response to catabolic or anabolic agents more physiologically relevant

Prosthetic joint infections (PJI) occur in 0.8–1.9 % of arthroplasties, but the absolute number is increasing because of the frequency of procedures. Two stage exchange is the most effective strategy, but failures are often described. Culture of perioperative tissues during removal of arthroplasty is a standard procedure but culture during second step is equally important to define a success or a failure. We retrospectively reviewed PJI treated with two stage-exchange from January 2011 and December 2012 at “Ospedale S. Maria Misericordia”, Albenga-Italy. The procedure calls for bacterial culture not only during first step but also during reimplantation. Antibiotic treatment is prolonged after reimplantation until the cultures availability. A failure was defined by persistence of infection for positive culture or reocurrence of infection during a follow up of at least 2 years in patients with negative cultures. Three positive cultures yielding phenotypically identical organisms, or a single specimen of a virulent microorganism (e.g. Staphylococcus aureus) were required to rule out false positive for contaminants. Patients with persistence of infection were treated for 3 months with antibiotics. 86 patients underwent the two stage treatment: 45 hip and 41 knee prosthesis. The average ESR before arthroplasty removal was 59 mm/ 1st h (range 5–120), the average CRP was 3.9 mg/dl (range 0.3 – 34). Coagulase-negative staphylococci were isolated in 31 cases, Staphylococcus aureus in 19, Streptococcus spp in 8 and enterococci in 4. Gram-negatives were isolated in 4 patients and polymicrobial infection in 6 patients. In 14 patients (16%) no pathogen was identified. A positive culture during reimplantation was documented in 11 (13%) cases: 8 coagulase-negative staphylococci, 2 Staphylococcus aureus, 1 Candida sp. All patients received 3 months of therapy after surgery and 6 of them were free of infection at 2 years of follow up after the end of treatment. Among the 75 patients with negative cultures, a relapse was documented in 2 (3%), after 5 and 24 months, respectively. These cases were treated with arthrodesis and 6 weeks antibiotic treatment, with resolution of infection but poor functional results. Overall the success rate of our strategy was 92% (79/86). In patients treated with two-stage exchange, the combination of cultures at reimplantation and antibiotic suppressive treatment for 3 months in presence of positive cultures, are associated with a high rate of success. Only a prolonged follow up can rule out a relapse and agree with a true resolution of infection