The concordance between preoperative aspiration and intraoperative synovial fluid culture results: intraoperative synovial fluid re-cultures are necessary whether the preoperative aspiration culture is positive or not

Aims Preoperative aspiration culture and intraoperative cultures play pivotal roles in periprosthetic joint infection (PJI) diagnosis and pathogen identification. But the discordance between preoperative aspiration culture and intraoperative synovial fluid culture remains unknown. We aim to determine (1) the discordance between preoperative and intraoperative synovial fluid (SF) culture and. (2) compared to intraoperative synovial fluid cultures, the sensitivity of preoperative aspiration fluid culture. Then the following question is tried to be answered: Are intraoperative synovial fluid re-cultures necessary if the preoperative aspiration culture is positive? Materials and methods Between 2015 and 2019, 187 PJI patients managed with surgeries were included in this study. Compared to intraoperative synovial fluid culture, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of preoperative aspiration culture were calculated. Then, the discordance between preoperative aspiration culture and intraoperative SF culture was analyzed. Results The sensitivity of preoperative aspiration culture was 81.29% compared to intraoperative synovial fluid cultures. Concordance was identified in 147 PJI (78.61%) patients and culture discordance occurred in 40 patients (21.39%). In these discordant PJI patients, 24 patients (60%) were polymicrobial and no intraoperative synovial fluid culture growth was found in 16 PJI cases (40%). Preoperative monomicrobial staphylococcus results had a sensitivity of and a specificity of 80.43% and 83.16%, respectively. Preoperative polymicrobial results had the lowest sensitivity. Conclusions The intraoperative synovial fluid re-cultures are necessary if the preoperative aspiration culture is positive and the discordance between preoperative aspiration culture and intraoperative synovial fluid culture should be noted especially when Streptococcus spp. and more than one pathogen was revealed by preoperative aspiration culture. Level of evidence: Level III.

Native joint infections in Iceland 2003–2017: an increase in postarthroscopic infections

ObjectivesNationwide study on the epidemiology, clinical characteristics and outcomes among patients with native joint infection (NJI) in Iceland, 2003–2017.MethodsAll positive synovial fluid culture results in Iceland were identified and medical records reviewed.ResultsA total of 299 NJI (40 children and 259 adults) were diagnosed in Iceland in 2003–2017, with a stable incidence of 6.3 cases/100 000/year, but marked gender difference among adults (33% women vs 67% men, p<0.001). The knee joint was most commonly affected, and Staphylococcus aureus was the most common isolate in both adults and children, followed by various streptococcal species in adults and Kingella kingae in children. NJI was iatrogenic in 34% of adults (88/259) but comprised 45% among 18–65 years and a stable incidence. Incidence of infections following arthroscopic procedures in adults increased significantly compared with the previous decade (9/100 000/year in 1990–2002 vs 25/100 000/year in 2003–2017, p<0.01) with no significant increase seen in risk per procedure. The proportion of postarthroscopic NJI was 0.17% overall but 0.24% for knee arthroscopy. Patients with postarthroscopic infection were more likely to undergo subsequent arthroplasty when compared with other patients with NJI (p=0.008).ConclusionsThe incidence of NJI in Iceland has remained stable. The proportion of iatrogenic infections is high, especially among young adults, with an increase seen in postarthroscopic infections when compared with the previous decade. Although rare, NJI following arthroscopy can be a devastating complication, with significant morbidity and these results, therefore, emphasise the need for firm indications when arthroscopic treatment is considered.

The Role of Biopsy in Diagnosing Infection After Hip and Knee Arthroplasty: A Meta-Analysis

Background Early diagnosis of periprosthetic hip and knee infection still represents a major challenge, as no single test can achieve ideal results. Currently, multiple preoperative indicators were performed to diagnose periprosthetic joint infection (PJI) to confirm or exclude infection in the early stage. However, the diagnostic value of biopsy-related tests in diagnosing periprosthetic hip and knee infection remains unclear.Methods Publications in PubMed, Embase, and the Web of Science databases were searched systematically until October 2020. Inclusion and exclusion criteria were used for screening biopsy-related studies of the diagnosis of periprosthetic hip and knee infection. All relevant tests were analyzed using Meta-Disc. For comparison between biopsy-related and conventional diagnostic methods in the diagnosis of PJI, the sensitivity and specificity of selected studies were calculated in the subgroup and compared using the z-test. Quality assessment of the selected literature was performed using the Quality Assessment of Diagnostic Accuracy Studies.Results Three biopsy-related tests were identified in 14 articles and further analyzed in the present meta-analysis. The pooled sensitivity and specificity was 0.90 (95% confidence interval [CI], 0.87–0.93), 0.97 (95% CI, 0.95–0.98) for the combined method (microbial culture plus histology), 0.76 (95% CI: 0.71–0.80) and 0.94 (95% CI: 0.91–0.95) for microbiological tests, and 0.62 (95% CI: 0.45–0.77), 0.97 (95% CI: 0.92–0.99) for histology. The pooled diagnostic odds ratios for diagnosing PJI using the combined method, microbiological test, and histology were 229.61 (95% CI: 94.90–555.56), 40.44 (95% CI: 23.74–68.89), and 54.47 (95% CI: 11.66–254.43), respectively. The combined method had the highest value for the area under the curve (0.9805), followed by histology (0.9425) and microbiological tests (0.9292). In the subgroup, statistical differences were identified in sensitivity and specificity for PJI diagnosis between the synovial fluid culture and biopsy culture group (P＜0.001), as well as in the biopsy-related combined method and serum C-reactive protein (CRP; P＜0.001).ConclusionsBiopsy culture does not appear to be advantageous compared to synovial fluid culture in the preoperative diagnosis of periprosthetic hip and knee infection. In contrast, combined biopsy microbial culture with histology analysis shows great potential in improving the preoperative diagnosis of PJI. The standard procedure of biopsy needs to be further explored. Further research is required to verify our results.

The Concordance between Preoperative Aspiration and Intraoperative Synovial Fluid Culture Results: Intraoperative Synovial Fluid Re-Cultures Are Necessary whether the Preoperative Aspiration Culture is Positive or Not.

Aims: Preoperative aspiration culture and intraoperative cultures play pivotal roles in periprosthetic joint infection (PJI) diagnosis and pathogen identification. But the discordance between preoperative aspiration culture and intraoperative synovial fluid culture remains unknown. We aim to determine 1）the discordance between preoperative and intraoperative synovial fluid (SF) culture and. 2) compared to intraoperative synovial fluid cultures, the sensitivity of preoperative aspiration fluid culture. Then the following question is tried to be answered: Are intraoperative synovial fluid re-cultures necessary if the preoperative aspiration culture is positive?Materials and methods:Between 2015 and 2019, 187 PJI patients managed with surgeries were included in this study. Compared to intraoperative synovial fluid culture, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of preoperative aspiration culture were calculated. Then, the discordance between preoperative aspiration culture and intraoperative SF culture was analyzed. Results:The sensitivity of preoperative aspiration culture was 81.29% compared to intraoperative synovial fluid cultures. Concordance was identified in 147 PJI (78.61%) patients and culture discordance occurred in 40 patients (21.39%). In these discordant PJI patients, 24 patients (60%) were polymicrobial and no intraoperative synovial fluid culture growth was found in 16 PJI cases (40%). Preoperative monomicrobial staphylococcus results had a sensitivity of and a specificity of 80.43% and 83.16%, respectively. Preoperative polymicrobial results had the lowest sensitivity.Conclusions: The intraoperative synovial fluid re-cultures are necessary if the preoperative aspiration culture is positive and the discordance between preoperative aspiration culture and intraoperative synovial fluid culture should be noted especially when streptococcus spp. and more than one pathogen was revealed by preoperative aspiration culture.

Primary meningococcal arthritis in a COVID-19 18-year-old man: a case report and review of the literature

Background SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection is associated with various complications. PMA (primary meningococcal arthritis) is a rare meningococcus-associated disease causing arthritis of the knee usually, without any signs of invasive meningococcal disease. No case of PMA in a COVID-19 (coronavirus disease, 2019) patient has yet been described. PMA mainly strikes young adults. PMA is not associated with any immunocompromising condition. It has a better outcome than usual septic arthritis Case presentation Herein, we report an 18-year-old man diagnosed with COVID-19, later admitted with persistent fever, right knee arthralgia and maculopapular rash. Due to family history, psoriasis and Henoch-Schönlein purpura were hypothesized and ruled out. Finally, synovial fluid culture confirmed Neisseria meningitidis serogroup B arthritis without any other symptoms of invasive meningococcal disease. Healing was achieved quickly with surgery and antibiotics. We concluded in a PMA. Conclusion We describe here the first primary meningococcal arthritis in a COVID-19 patient and we hope to shine a light on this rare but serious complication.

Preoperative synovial fluid culture poorly predicts the pathogen causing periprosthetic joint infection

Purpose We investigated the value of preoperative pathogen detection and evaluated its concordance with intraoperative cultures in patients with culture-positive periprosthetic joint infection (PJI). Methods Culture-positive PJI episodes with available preoperative (synovial fluid) and intraoperative cultures (periprosthetic tissue, synovial or sonication fluid) were analyzed. The pathogen detection rate in preoperative and intraoperative cultures was compared using Fisher’s exact test and their concordance was calculated. Results Among 167 included PJI episodes, 150 were monomicrobial with coagulase-negative staphylococci (n = 55, 37%), S. aureus (n = 34, 23%), and streptococci (n = 21, 14%) being the most common pathogens. Seventeen episodes (10%) were polymicrobial infections. The pathogen(s) grew in preoperative culture in 110 and in intraoperative cultures in 153 episodes (66% vs. 92%, p < 0.001). The pathogen detection rate was lower in preoperative compared to intraoperative cultures for low-virulent pathogens (40% vs. 94%, p < 0.001), polymicrobial infections (59% vs. 100%, p = 0.007), and in delayed and late PJI (63% vs. 94%, and 66% vs. 91%, respectively, p < 0.001). Full concordance of preoperative and intraoperative cultures was found in 87 episodes (52%). The pathogen was detected solely preoperatively in 14 episodes (8%) and solely intraoperatively in 57 cases (34%); an additional pathogen was found in 3 episodes (2%) preoperatively and in 6 episodes (4%) intraoperatively. Conclusion The concordance of preoperative and intraoperative cultures was poor (52%). The sole or an additional pathogen was found exclusively in intraoperative cultures in 38% of PJI episodes, hence preoperative synovial fluid cultures are considered unreliable for pathogen detection in PJI.

New Methods in the Diagnosis of Prosthetic Joint Infection

A timely and accurate diagnosis of periprosthetic joint infection (PJI) is crucial to plan adequate treatment. Purpose of the study. To evaluate the performance of new diagnostic tests for the diagnosis of PJI. Material and Methods. The performance of novel biomarkers in synovial fluid (i.e. D-lactate and alfa-defensin), molecular test (i.e. PCR of synovial fluid and sonication fluid), new methods to dislodge biofilm from implant surface (i.e. MicroDTTect) and sonication of explanted prosthesis were investigated in patients with PJI and aseptic loosening of the prosthesis. Results. D-lactate showed better sensitivity for the diagnosis of PJI compared to leukocyte count (86% and 80%, respectively). The optimal D-lactate cut-off value was calculated at 1.26 mmol/l. The ADLF test showed sensitivity of 84%, 67% and to 54% depending on classification criteria used for the diagnosis of PJI (Musculoskeletal Infection Society (MSIS), The Infectious Diseases Society of America (IDSA) and proposed European Bone and Joint Infection Society (EBJIS) criteria, respectively). Using the proposed EBJIS definition criteria, the sensitivity of the leukocyte count was significantly higher than that of the ADLF test (86% compared with 54%; p<0,001), particularly in chronic PJI (81% compared with 44%, respectively; p<0,001). The sensitivity of synovial fluid PCR was 60% and herewith comparable with synovial fluid culture (52%, p = 0,239). The sensitivity and specificity of sonication fluid culture were 58% and 100%, which was comparable to sonication fluid PCR 51% and 94%, respectively. DTT-based method showed low sensitivity for diagnosis of PJI (40%) compared to sonication (80%, p<0,01). Conclusion. Synovial fluid D-lactate demonstrated good analytical performance and diagnostic value for the diagnosis of PJI. In particular, the high sensitivity for diagnosing infection and rapid availability of the test result make synovial fluid D-lactate suitable as screening test, whereas ADLF had limited sensitivity (54%) but high specificity (>95%) and it should therefore not be used for screening, but rather as a confirmatory test for PJI. Multiplex PCR of synovial fluid and sonication fluid has similar sensitivity and specificity compared to synovial fluid culture, having the advantage of rapid availability of results (within 5 hours) and fully automated process. With further improvement of its performance and inclusion of additional primers, multiplex PCR may complement conventional cultures, especially for rapid and accurate diagnosis of low-grade PJI. Culture of samples obtained by sonication of prostheses showed better sensitivity for the microbiologic diagnosis of prosthetic hip and knee infection compared to chemical based dislodgement such as MicroDTTect.

Performance of automated multiplex polymerase chain reaction (mPCR) using synovial fluid in the diagnosis of native joint septic arthritis in adults

Aims This study aimed to assess the performance of an automated multiplex polymerase chain reaction (mPCR) technique for rapid diagnosis of native joint septic arthritis Patients and Methods Consecutive patients with suspected septic arthritis undergoing aseptic diagnostic joint aspiration were included. The aspirate was used for analysis by mPCR and conventional microbiological analysis. A joint was classed as septic according to modified Newman criteria. Based on receiver operating characteristic (ROC) analysis, the area under the ROC curve (AUC) values of the mPCR and the synovial fluid culture were compared using the z-test. A total of 72 out of 76 consecutive patients (33 women, 39 men; mean age 64 years (22 to 92)) with suspected septic arthritis were included in this study. Results Of 72 patients, 42 (58%) were deemed to have septic joints. The sensitivity of mPCR and synovial fluid culture was 38% and 29%, respectively. No significant differences were found between the AUCs of both techniques (p = 0.138). A strong concordance of 89% (Cohen’s kappa: 0.65) was shown. The mPCR failed to detect Staphylococcus aureus (n = 1) and Streptococcus pneumoniae (n = 1; no primer included in the mPCR), whereas the synovial fluid culture missed six microorganisms (positive mPCR: S. aureus (n = 2), Cutibacterium acnes (n = 3), coagulase-negative staphylococci (n = 2)). Conclusion The automated mPCR showed at least a similar performance to the synovial fluid culture (the current benchmark) in diagnosing septic arthritis, having the great advantage of a shorter turnaround time (within five hours). Cite this article: Bone Joint J 2019;101-B:288–296.

Synovial Fluid Aspiration Should Not Be Routinely Performed during the Two-Stage Exchange of the Knee

Purpose. Detection of infection persistence during the two-stage exchange of the knee for periprosthetic joint infection is challenging. Synovial fluid culture (SFC) and synovial white blood cell count (SWBCC) before joint reimplantation are widespread diagnostic means for this indication. The sensitivity and specificity of SFC and of SWBCC for infection persistence before planned reimplantation were evaluated. Methods. 94 two-stage exchanges of the knee with synovial fluid aspiration performed after a drug holiday of at least 14 days and before reimplantation or spacer exchange (planned reimplantation) were retrospectively analyzed. Only cases with at least 3 intraoperative samples at planned reimplantation were included. SFC and SWBCC were compared to pathogen detection (SFC(culture)/SWBCC(culture)) and to histopathological signs of infection persistence (SFC(histo)/SWBCC(histo)) from intraoperative samples at planned reimplantation. For SFC, the sensitivity and specificity were calculated. For SWBCC, the optimal cut-off value with its sensitivity and specificity was calculated with the Youden-Index. Results. Sensitivity and specificity of SFC(culture) were 0.0% and 98.9%. Sensitivity and specificity of SFC(histo) were 3.4% and 100%. The optimal cut-off value for SWBCC(culture) was 4450 cells/μl with a sensitivity of 50.0% and a specificity of 86.5%. The optimal cut-off value for SWBCC(histo) was 3250 cells/μl with a sensitivity of 35.7% and a specificity of 92.9%. Conclusion. The detection of infection persistence remains challenging and a consented approach is lacking. The results do not warrant the routine performance of SFC during the two-stage exchange at the knee. SWBCC can be used to confirm infection persistence at high cut-offs, but they only occur in few patients and are therefore inappropriate for the routine use.