Comparison of cultures and 16S rRNA sequencing for identification of bacteria in two-stage revision arthroplasties: preliminary report

Impact of Positive Cultures During the Second Stage of a Two-Stage Exchange: Systematic Review and Meta-Analysis

BACKGROUND

Two-stage exchange is a frequently performed procedure in patients who have a periprosthetic joint infection. Positive cultures when performing the second stage are perceived as a risk factor for reinfection. This study aimed to determine the impact of positive cultures during the second stage on the outcome of patients undergoing a 2-stage septic exchange and the impact of stopping the antibiotic treatment before reimplantation.

METHODS

We systematically searched four databases. We performed a meta-analysis on the risk of complications after positive cultures during second stage and a subgroup analysis by antibiotic holiday period. We included 24 studies.

RESULTS

Failure in the positive group was 37.0% and in the negative group was 13.7% with an odds ratio (OR) of 4.05. In the subgroup analysis by antibiotic holidays, failure rate without holidays was 15% and with holidays was 17.3% (P = .21). Failure in each group was higher when cultures were positive (without holidays, 25 versus 12.2%, P = .0003, and with holidays 41.1 versus 12.7%, P < .0001), but the risk of failure when cultures were positive was higher in the holiday group (OR 4.798) than in the nonholiday group (OR 2.225) in comparison to those patients who were culture negative at the second stage.

CONCLUSIONS

Microbiological eradication at second stage was not obtained in 18% of cases and it was associated with a higher failure rate. In patients with positive cultures, withholding antibiotic treatment was associated with lower failure rate. Further studies to define the antibiotic strategy in 2-stage exchange procedure are necessary.

The Use of Intraoperative Cell Salvage in Two-Stage Revision of Septic Hip Arthroplasties: A Double-Center Retrospective Study

(1) Background: intraoperative cell salvage (ICS) devices can provide a valuable contribution to patient blood management. An infection of the surgical site presents a formal contraindication to the use of ICS. To date, there is no recommendation for the use of ICS in the context of reimplantation in two-stage septic exchange arthroplasty. (2) Methods: at two hospitals of maximum endoprosthetic care, a retrospective evaluation of patients who had received ICS blood during reimplantation of hip arthroplasties was performed. Patients' and surgical characteristics, intraoperative cultures, and the occurrence of septic complications in the short- and long-term follow-up were recorded. (3) Results: 144 patients were included. Detection of positive cultures during reimplantation occurred in 13 cases. A total of 127 patients showed no complication, 8 patients showed a non-specific septic complication, 6 patients a local persistence of infection, and 3 patients a possible bloodstream-associated infection. No significant correlation was found between the occurrence of complications and the detection of positive intraoperative cultures. (4) Conclusions: no clustering of septic complications due to the use of ICS during reimplantation was found. In the risk-benefit analysis, we considered the use of ICS during reimplantation to be indicated in terms of patient blood management, while the safety of the procedure during septic first-stage resection arthroplasty or septic one-stage exchange arthroplasty was not investigated. Given the paucity of comparative literature, further studies are needed on ideal patient blood management in the setting of septic revision arthroplasty.

Comparable clinical outcomes of culture-negative and culture-positive periprosthetic joint infections: a systematic review and meta-analysis

PURPOSE

The aim of this study was to compare the clinical outcomes of culture-negative periprosthetic joint infection (CN PJI) with those of culture-positive periprosthetic joint infection (CP PJI).

METHODS

Data were obtained from Embase, Web of Science and EBSCO for all available studies comparing the clinical outcomes of CN PJI with those of CP PJI. The quality of the studies was scored using the Newcastle-Ottawa scale (NOS). Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess clinical outcomes. Subgroup analyses were performed to explain heterogeneity among the included studies. Publication bias was estimated using Begg's funnel plot. Sensitivity analysis was performed to test the stability of pooled results.

RESULTS

Thirty studies with 1630 (38.7%) CN PJI and 2577 (61.3%) CP PJI were included in this meta-analysis. The pooled results of the included studies showed that overall failure rate in CN PJI group (19.0%, 309/1630) was significantly lower than that in CP PJI group (23.4%, 604/2577) (OR 0.63, 95% CI 0.47-0.84, P = 0.002). We performed the subgroup analysis based on the surgical strategies, the pooled results of nine studies for patients undergoing debridement, antibiotics and implant retention (DAIR) revealed that failure rate in CN PJI group (22.2%, 53/239) was significantly lower than that in CP PJI group (29.3%, 227/775) (OR 0.62, 95% CI 0.43-0.90, P = 0.01), the pooled results of four studies for patients undergoing one-stage revision revealed that failure rate between CN PJI group (11.5%, 11/96) and CP PJI group (7.6%, 27/355) had no significant difference (OR 1.57, 95% CI 0.75-3.26, P = 0.23), and the pooled results of 19 studies for patients undergoing two-stage revision revealed that failure rate in CN PJI group (16.1%, 171/1062) was significantly lower than that in CP PJI group (20.4%, 206/1010) (OR 0.52, 95% CI 0.34-0.79, P = 0.002).

CONCLUSIONS

CN PJI group had similar or better survival rate when compared with CP PJI group for patients who underwent DAIR, one-stage or two-stage revision. Negative culture was not a worse prognostic factor for PJI.

Utility of Diagnostic Tests Before Reimplantation in Patients Undergoing 2-Stage Revision Total Joint Arthroplasty: A Systematic Review and Meta-analysis

INTRODUCTION

Periprosthetic joint infection (PJI) is a devastating complication after total joint arthroplasty (TJA), with treatment failure occurring in 12% to 28% after 2-stage revision. It is vital to identify diagnostic tools indicative of persistent infection or treatment failure after 2-stage revision for PJI.

METHODS

The Cochrane Library, PubMed (MEDLINE), and EMBASE were searched for randomized controlled trials and comparative observational studies published before October 3, 2021, which evaluated the utility of serum/plasma biomarkers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], interleukin-6 [IL-6], fibrinogen, D-dimer), synovial biomarkers (white blood cell [WBC] count, neutrophil percentage [PMN %], alpha-defensin [AD], leukocyte esterase [LE]), tissue frozen section, tissue culture, synovial fluid culture, or sonicated spacer fluid culture indicative of persistent infection before the second stage of 2-stage revision for PJI or treatment failure after 2-stage revision for PJI.

RESULTS

A total of 47 studies including 6,605 diagnostic tests among 3,781 2-stage revisions for PJI were analyzed. Among those cases, 723 (19.1%) experienced persistent infection or treatment failure. Synovial LE (sensitivity 0.25 [0.10-0.47], specificity 0.99 [0.93-1.00], positive likelihood ratio 14.0 [1.45-135.58]) and serum IL-6 (sensitivity 0.52 [0.33-0.70], specificity 0.92 [0.85-0.96], positive likelihood ratio 7.90 [0.86-72.61]) had the highest diagnostic accuracy. However, no biomarker was associated with a clinically useful negative likelihood ratio. In subgroup analysis, synovial PMN %, synovial fluid culture, serum ESR, and serum CRP had limited utility for detecting persistent infection before reimplantation (positive likelihood ratios ranging 2.33-3.74; negative likelihood ratios ranging 0.31-0.9) and no utility for predicting failure after the second stage of 2-stage revision.

CONCLUSIONS

Synovial WBC count, synovial PMN %, synovial fluid culture, serum ESR, and serum CRP have modest sensitivity and specificity for predicting persistent infection during the second stage of 2-stage revision, suggesting some combination of these diagnostic tests might be useful before reimplantation. No biomarker or culture accurately predicted treatment failure after reimplantation.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.

Periprosthetic Joint Infection (PJI)—Results of One-Stage Revision with Antibiotic-Impregnated Cancellous Allograft Bone—A Retrospective Cohort Study

Controversy exists regarding the optimal treatment of periprosthetic joint infection (PJI), considering control of infection, functional results as well as quality of life. Difficulties in treatment derive from the formation of biofilms within a few days after infection. Biofilms are tolerant to systemically applied antibiotics, requiring extreme concentrations for a prolonged period. Minimum biofilm eradicating concentrations (MBEC) are only feasible by the local application of antibiotics. One established approach is the use of allograft bone as a carrier, granting a sustained release of antibiotics in very high concentrations after appropriate impregnation. The purpose of this study was to determine the rate of reinfection after a one-stage revision of infected hip or knee prostheses, using antibiotic-impregnated allograft bone as the carrier and avoiding cement. Between 1 January 2004 and 31 January 2018, 87 patients with PJI, according to MSIS, underwent a one-stage revision with antibiotic-impregnated cancellous allograft bone. An amount of 17 patients had insufficient follow-ups. There were 70 remaining patients (34 male, 36 female) with a mean follow-up of 5.6 years (range 2–15.6) and with a mean age of 68.2 years (range 31.5–86.9). An amount of 38 hips and 11 knees were implanted without any cement; and 21 knees were implanted with moderate cementing at the articular surface with stems always being uncemented. Within 2 years after surgery, 6 out of 70 patients (8.6%, CI 2–15.1) showed reinfection and after more than 2 years, an additional 6 patients showed late-onset infection. Within 2 years after surgery, 11 out of 70 patients (15.7%, CI 7.2–24.2) had an implant failure for any reason (including infection) and after more than 2 years, an additional 7 patients had an implant failure. Using Kaplan-Meier analysis for all 87 patients, the estimated survival for reinfection was 93.9% (CI 88.8–99.1) at 1 year, 89.9% (CI 83.2–96.6) at 2 years and 81.5% (CI 72.1–90.9) at 5 years. The estimated survival for implant failure for any reason was 90.4% (CI 84.1–96.7) at 1 year, 80.9% (CI 72.2–89.7) at 2 years and 71.1% (CI 60.3–81.8) at 5 years. One-stage revision with antibiotic-impregnated cancellous allograft bone grants comparable results regarding infection control as with multiple stages, while shortening rehabilitation, improving quality of life for the patients and reducing costs for the health care system.

Biofilm microbiome in extracorporeal membrane oxygenator catheters

Despite the formation of biofilms on catheters for extracorporeal membrane oxygenation (ECMO), some patients do not show bacteremia. To elucidate the specific linkage between biofilms and bacteremia in patients with ECMO, an improved understanding of the microbial community within catheter biofilms is necessary. Hence, we aimed to evaluate the biofilm microbiome of ECMO catheters from adults with (n = 6) and without (n = 15) bacteremia. The microbiomes of the catheter biofilms were evaluated by profiling the V3 and V4 regions of bacterial 16s rRNA genes using the Illumina MiSeq sequencing platform. In total, 2,548,172 reads, with an average of 121,341 reads per sample, were generated. Although alpha diversity was slightly higher in the non-bacteremic group, the difference was not statistically significant. In addition, there was no difference in beta diversity between the two groups. We found 367 different genera, of which 8 were present in all samples regardless of group; Limnohabitans, Flavobacterium, Delftia, Massilia, Bacillus, Candidatus, Xiphinematobacter, and CL0-1 showed an abundance of more than 1% in the sample. In particular, Arthrobacter, SMB53, Neisseria, Ortrobactrum, Candidatus Rhabdochlamydia, Deefgae, Dyella, Paracoccus, and Pedobacter were highly abundant in the bacteremic group. Network analysis indicated that the microbiome of the bacteremic group was more complex than that of the non-bacteremic group. Flavobacterium and CL0.1, which were abundant in the bacteremic group, were considered important genera because they connected different subnetworks. Biofilm characteristics in ECMO catheters varied according to the presence or absence of bacteremia. There were no significant differences in diversity between the two groups, but there were significant differences in the community composition of the biofilms. The biofilm-associated community was dynamic, with the bacteremic group showing very complex network connections within the microbiome.

Deciphering the low abundance microbiota of presumed aseptic hip and knee implants

16S rRNA gene sequencing of DNA extracted from clinically uninfected hip and knee implant samples has revealed polymicrobial populations. However, previous studies assessed 16S rRNA gene sequencing as a technique for the diagnosis of periprosthetic joint infections, leaving the microbiota of presumed aseptic hip and knee implants largely unstudied. These communities of microorganisms might play important roles in aspects of host health, such as aseptic loosening. Therefore, this study sought to characterize the bacterial composition of presumed aseptic joint implant microbiota using next generation 16S rRNA gene sequencing, and it evaluated this method for future investigations. 248 samples were collected from implants of 41 patients undergoing total hip or knee arthroplasty revision for presumed aseptic failure. DNA was extracted using two methodologies-one optimized for high throughput and the other for human samples-and amplicons of the V4 region of the 16S rRNA gene were sequenced. Sequencing data were analyzed and compared with ancillary specific PCR and microbiological culture. Computational tools (SourceTracker and decontam) were used to detect and compensate for environmental and processing contaminants. Microbial diversity of patient samples was higher than that of open-air controls and differentially abundant taxa were detected between these conditions, possibly reflecting a true microbiota that is present in clinically uninfected joint implants. However, positive control-associated artifacts and DNA extraction methodology significantly affected sequencing results. As well, sequencing failed to identify Cutibacterium acnes in most culture- and PCR-positive samples. These challenges limited characterization of bacteria in presumed aseptic implants, but genera were identified for further investigation. In all, we provide further support for the hypothesis that there is likely a microbiota present in clinically uninfected joint implants, and we show that methods other than 16S rRNA gene sequencing may be ideal for its characterization. This work has illuminated the importance of further study of microbiota of clinically uninfected joint implants with novel molecular and computational tools to further eliminate contaminants and artifacts that arise in low bacterial abundance samples.

Diagnostic Value of 16S Ribosomal RNA Gene Polymerase Chain Reaction/Sanger Sequencing in Clinical Practice

BACKGROUND

Accurate microbiologic diagnosis is important for appropriate management of infectious diseases. Sequencing-based molecular diagnostics are increasingly used for precision diagnosis of infections. However, their clinical utility is unclear.

METHODS

We conducted a retrospective analysis of specimens that underwent 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR) followed by Sanger sequencing at our institution from April 2017 through March 2019.

RESULTS

A total of 566 specimens obtained from 460 patients were studied. Patients were considered clinically infected or noninfected based on final diagnosis and management. In 17% of patients, 16S rRNA PCR/sequencing was positive and in 5% of patients, this test led to an impact on clinical care. In comparison, bacterial cultures were positive in 21% of patients. Specimens with a positive Gram stain had 12 times greater odds of having a positive molecular result than those with a negative Gram stain (95% confidence interval for odds ratio, 5.2-31.4). Overall, PCR positivity was higher in cardiovascular specimens (37%) obtained from clinically infected patients, with bacterial cultures being more likely to be positive for musculoskeletal specimens (P < .001). 16S rRNA PCR/sequencing identified a probable pathogen in 10% culture-negative specimens.

CONCLUSION

16S rRNA PCR/sequencing can play a role in the diagnostic evaluation of patients with culture-negative infections, especially those with cardiovascular infections.

Diagnosing fracture related infections: Where are we now?

Accurate diagnosis of fracture related infection (FRI) is critical for preventing poor outcomes such as loss of function or amputation. Due to the multiple variables associated with FRI, however, accurate diagnosis is challenging and complicated by a lack of standardized diagnostic criteria. Limitations with the current gold standard for diagnosis, which is routine microbiology culture, further complicate the diagnostic and management process. Efforts to optimize the process rely on a foundation of data derived from prosthetic joint infections (PJI), but differences in PJI and FRI make it clear that unique approaches for these distinct infections are required. A more concerted effort focusing on FRI has dominated more recent investigations and publications leading to a consensus definition by the American Orthopedics (AO) Foundation and the European Bone and Joint Infection Society (EBJIS). This has the potential to better standardize the diagnostic process, which will not only improve patient care but also facilitate more robust and reproducible research related to the diagnosis and management of FRI. The purpose of this review is to explore the consensus definition, describe the foundation of data supporting current FRI diagnostic techniques, and identify pathways for optimization of clinical microbiology-based strategies and data.

Sonication fluid culture of antibiotic-loaded bone cement spacer has high accuracy to confirm eradication of infection before reimplantation of new prostheses

BACKGROUND

Sonication fluid culture of antibiotic-loaded bone cement spacer has been used to predict reinfection of two-stage revision, but its value remains disputable. This study aims to evaluate the association between the culture result of the sonicated spacer and the status of patients with periprosthetic joint infection receiving two-stage revision.

MATERIALS AND METHODS

A comprehensive electronic literature search was performed through four databases including PubMed, Embase/Ovid, and EBSCO, and the Cochrane Library to retrieve studies in which sonication fluid culture of the antibiotic spacer was conducted before reimplantation. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated to assess the association between the culture result of sonicated spacer and prognosis of the two-stage revision.

RESULTS

Eleven eligible studies comprising 603 artificial joints with PJI (134 suffering a clinical failure of two-stage revision) were included in the quantitative analysis. The pooled incidences of positive culture of sonicated spacer and intraoperative tissue were 0.14 (95% confidence interval [CI] 0.08-0.21) and 0.14 (95% CI 0.08-0.20), respectively. A positive culture of sonicated antibiotic-loaded bone cement spacer illustrated moderate sensitivity (0.31, 95% CI 0.13-0.58) but high specificity (0.94, 95% CI 0.86-0.98) for the diagnosis of therapeutic failure of two-stage revision; the pooled DOR was 7.67 (95% CI, 3.63-16.22). Meanwhile, the pooled sensitivity, specificity, and DOR of intraoperative tissue culture during the two-stage revision to predict therapeutic failure were 0.32 (95% CI, 0.20-0.47), 0.96 (95% CI, 0.92-0.98), and 10.62 (95% CI, 4.90-23.01), respectively.

CONCLUSIONS

Sonication fluid culture of antibiotic-loaded bone cement spacer revealed high accuracy for confirming eradication of infection before reimplantation of new prostheses and therefore could be used as a supplement for assessing therapeutic effect for PJI. However, both sonication fluid culture and intraoperative tissue culture from antibiotic-loaded bone cement spacer showed restricted yield for the prediction of a septic failure after the two-stage revision of PJI. Large-scale, prospective studies are still needed to testify current findings.

Propidium monoazide-polymerase chain reaction for detection of residual periprosthetic joint infection in two-stage revision

False negative culture results in periprosthetic joint infection (PJI) are not uncommon particularly when patients have received long term antibiotics. Polymerase chain reaction (PCR) has a lower specificity partly due to detection of residual DNA from dead bacteria. Propidium monoazide (PMA) prevents DNA from dead bacteria from being amplified during the PCR. This study aimed to determine the role of PMA in PCR for diagnosis of PJI. Clinical samples were tested by PCR with and without prior treatment with PMA and compared to conventional microbiological culture. The PCR assay included genus-specific primers for staphylococci and enterococci and species-specific primers for Cutibacterium acnes. The validated conditions of PMA treatment used in this study were 20 μM concentration and 5 and 10 min of dark incubation and photo-activation respectively. 202 periprosthetic tissues and explanted prostheses from 60 episodes in 58 patients undergoing revision arthroplasties for either PJI or non-infective causes were tested, by culture, PCR, and PMA-PCR. 14 of the 60 episodes satisfied the Musculoskeletal Infection Society (MSIS) criteria for PJI and 46 did not. Sensitivity of culture, PCR, and PMA-PCR were 50%, 71%, and 79% respectively. Specificities were 98%, 72%, and 89% respectively. All figures were calculated for episodes rather than samples. PMA-PCR enhanced both the specificity and the sensitivity of PCR. It has the potential to detect residual bacterial viability prior to reimplantation in the two-stage revision for PJI.

Intraoperative Cultures in Reimplantation of a Two-Stage Protocol: Only 1 vs. At Least 2 Positive Microbiological Results

Background:

The main reason for using a two-stage exchange in Prosthetic Joint Infection (PJI) is that bacteria are completely eradicated in reimplantation surgery. However, reports of a positive culture in the second surgery are growing. The number of positive intraoperative cultures and their influence on final results is not well-established.

Objectives:

To compare epidemiological characteristics, infection recurrence and clinical evolution of patients with only onevs.at least two positive cultures based on our series of cases with positive cultures in reimplantation surgery.

Material and Methods:

Retrospective study of 55 patients was conducted prospectively. They were diagnosed with chronic PJI, treated with a two-stage protocol and at least three intraoperative cultures were obtained in the second stage. These cultures were negative in 28 patients. Fourteen patients showed two or more cultures with the same microorganism and they were denominated patients with positive cultures. Thirteen patients showed only one positive culture, and they were considered contaminated. Both groups of patients (positive cultures and contaminated ones) received the second cycle of oral antibiotics for 6 months. Functional results were evaluated with the Harris Hip Score (hips) or Knee Society Clinical Rating Score (KSCRS) (knees).

Results:

There were no significant differences between patients with positive or contaminated cultures for age (p=0.420) and sex (p=0.385). The knee was involved in 13/14 positive and in only 6/13 contaminated patients (p=0.013).Staphylococcus epidermidiswas the predominant isolate, but there were differences between positive (methicillin-resistant in 7/14 patients) and contaminated cultures (methicillin-sensitive in 6/13). There were no differences in the prevalence of polymicrobial cultures (p=0.785) or coincidence with cultures from the first stage (p=0.257). Three infection recurrences have appeared in patients with positive cultures (3/13, 21%) and none in patients with contaminated cultures. There are no differences in HSS or KSCRS when comparing final functional results between groups (p=0.411).

Conclusion:

The prevalence of positive cultures in reimplantation surgery is higher than expected (25%), and more frequent in women and in knee arthroplasties. The most frequently involved microorganism isStaphylococcus epidermidis, but antibiotic sensitivity varies between patients with positive cultures (methicillin-resistant) and those with contaminated cultures (methicillin-sensitive). There were no infection recurrences in patients with contaminated cultures, but those with positive cultures present a risk of over 20%.

Positive Culture During Reimplantation Increases the Risk of Reinfection in Two-Stage Exchange Arthroplasty Despite Administrating Prolonged Antibiotics: A Retrospective Cohort Study and Meta-Analysis

BACKGROUND

The significance of a positive culture at reimplantation remains an important topic of consideration given the lack of clear metrics for when reimplantation can be performed. The purpose of this study is thus to investigate the (1) association between a positive culture during reimplantation and failure following 2-stage exchange arthroplasty and the (2) influence of prolonged antibiotics on these patients.

METHODS

We retrospectively reviewed 117 patients undergoing 2-stage exchange hip arthroplasty from 2012 to 2016. Of them, 23 had positive culture during reimplantation and were treated with 2 weeks of intravenous and 4 weeks of oral antibiotics following reimplantation. All patients had a minimum follow-up of 1 year. Logistic regression models were performed to identify association between positive culture and subsequent treatment failure. A meta-analysis was also performed to validate findings. A subgroup analysis was performed to explore whether 6-week antibiotics (oral, intravenous, or both) after reimplantation improved outcomes.

RESULTS

A total of 11 studies, which included 141 cases with a positive culture at reimplantation and 784 with negative cultures, were included in the meta-analysis. The pooled data showed a higher risk of failure in patients with a positive culture than those with a negative culture (41.1% vs 14.8%, odds ratio 4.58). The subgroup analysis revealed that 6 weeks of antibiotic administration following reimplantation decreased the odds of reinfection from 9.35 to 3.12. The findings in the retrospective cohort were consistent with those of the meta-analysis; the failure rate was significantly higher in patients with a positive culture than those with negative cultures (26.1% vs 6.4%, P < .001).

CONCLUSION

Six weeks of antibiotics appear to decrease the odds of reinfection after reimplantation. However, despite patients receiving 6 weeks of antibiotics after reimplantation, the risk of reinfection in patients with a positive culture at reimplantation is still more than 3 times higher than those with negative cultures. Further studies are needed to investigate optimal management for such patients.

Tests for predicting reimplantation success of two-stage revision for periprosthetic joint infection: A systematic review and meta-analysis

BACKGROUND

Several tests are used before reimplantation to detect persistent infection in patients with periprosthetic joint infection (PJI) undergoing two-stage revision. However, there is no consensus as to the optimal tests for excluding persistent infection or predicting successful reimplantation by stage. We aimed to determine the accuracy of different tests used to detect persistent infection after the first stage, and/or predicting failure following reimplantation in patients with PJI.

METHODS

We conducted a systematic review and meta-analysis of PubMed, Embase and the Cochrane Library databases. Two reviewers independently conducted quality assessments and data extractions to estimate pooled sensitivity and specificity, diagnostic odds ratio and area under the receiver operating characteristic curves (AUSROC) for each test.

RESULTS

We included 24 studies published between May 1999 and September 2017. Synovial fluid polymorphonuclear neutrophils (PMN)% had the highest sensitivity of 0.70, followed by serum erythrocyte sedimentation rate (0.57) and spacer sonication fluid culture (0.53). Synovial fluid culture had the highest specificity of 0.97, followed by frozen section (0.93) and the Musculoskeletal Infection Society criteria (0.92). Spacer sonication fluid culture was the most accurate test with an AUSROC of 0.8089, followed by synovial fluid culture (0.7749) and frozen section (0.7819).

DISCUSSION

Spacer sonication fluid culture had a relatively high diagnostic accuracy. We emphasize that no test can be used alone to exclude persistent infection beyond the first stage and/or predict failed reimplantation beyond the second stage.

LEVEL OF EVIDENCE

II, systematic review and meta-analysis of level 2 to level 4 studies with inconsistent results.

Cerclages after Femoral Osteotomy Are at Risk for Bacterial Colonization during Two-Stage Septic Total Hip Arthroplasty Revision

Aims: In cases of a two-stage septic total hip arthroplasty (THA) exchange a femoral osteotomy with subsequent cerclage stabilization may be necessary to remove a well-fixed stem. This study aims to investigate the rate of bacterial colonization and risk of infection persistence associated with in situ cerclage hardware in two-stage septic THA exchange.

Patients and Methods: Twenty-three patients undergoing two-stage THA exchange between 2011 and 2016 were included in this retrospective cohort study. During the re-implantation procedure synovial fluid, periprosthetic tissue samples and sonicate fluid cultures (SFC) of the cerclage hardware were acquired.

Results: Seven of 23 (30%) cerclage-SFC produced a positive bacterial isolation. Six of the seven positive cerclage-SFC were acquired during THA re-implantation.

Two of the seven patients (29%) with a positive bacterial isolation from the cerclage hardware underwent a THA-revision for septic complications. The other five patients had their THA in situ at last follow-up.

Conclusions: Despite surgical debridement and antimicrobial therapy, a bacterial colonization of cerclage hardware occurs and poses a risk for infection persistence. All cerclage hardware should be removed or exchanged during THA reimplantation.

Combination of conventional culture, vial culture, and broad-range PCR of sonication fluid for the diagnosis of prosthetic joint infection

We assessed the value of conventional culture, vial culture, and broad-range PCR of the sonication fluid (SF), individually or in combinations, for the diagnosis of prosthetic joint infection (PJI). We studied 114 consecutive patients (median age:72.5 years, males: 28.07%) undergoing removal of a total knee or hip prosthesis. By non-microbiologic criteria, 87 patients had aseptic failure, and 27 PJI. All patients had periprosthetic tissue culture, sonication of prosthesis, and study of SF by conventional and vial culture, and PCR. Compared to tissue culture, each test was significantly more sensitive and less specific. If only one test was positive, the sensitivity was 88.46% and specificity 64.29%. If all three SF tests were positive, sensitivity, and NPV were decreasing (34.6% and 80.23%), but specificity and PPV were increasing up to 98.57% and 90.9%, respectively, outperforming tissue culture. A triple negative test practically excluded PJI.

Diagnosis Of Persistent Infection In Prosthetic Two-Stage Exchange: PCR analysis of Sonication fluid From Bone Cement Spacers

Introduction: When treating periprosthetic joint infections with a two-stage procedure, antibiotic-impregnated spacers are used in the interval between removal of prosthesis and reimplantation. According to our experience, cultures of sonicated spacers are most often negative. The objective of our study was to investigate whether PCR analysis would improve the detection of bacteria in the spacer sonication fluid. Methods: A prospective monocentric study was performed from September 2014 to January 2016. Inclusion criteria were two-stage procedure for prosthetic infection and agreement of the patient to participate in the study. Beside tissues samples and sonication, broad range bacterial PCRs, specific S. aureus PCRs and Unyvero-multiplex PCRs were performed on the sonicated spacer fluid. Results: 30 patients were identified (15 hip, 14 knee and 1 ankle replacements). At reimplantation, cultures of tissue samples and spacer sonication fluid were all negative. Broad range PCRs were all negative. Specific S. aureus PCRs were positive in 5 cases. We had two persistent infections and four cases of infection recurrence were observed, with bacteria different than for the initial infection in three cases. Conclusion: The three different types of PCRs did not detect any bacteria in spacer sonication fluid that was culture-negative. In our study, PCR did not improve the bacterial detection and did not help to predict whether the patient will present a persistent or recurrent infection. Prosthetic 2-stage exchange with short interval and antibiotic-impregnated spacer is an efficient treatment to eradicate infection as both culture- and molecular-based methods were unable to detect bacteria in spacer sonication fluid after reimplantation.