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BackgroundSonication is a valuable tool in the diagnosis of periprosthetic joint infections (PJI). However, conditions and definition criteria for PJI vary among studies. The aim of this study was to determine the diagnostic performance (i.e., specificity, sensitivity) of sonicate fluid culture (SFC) against periprosthetic tissue culture (PTC), when using European Bone and Joint Infection Society (EBJIS) criteria.MethodsFrom March 2017 to April 2018, 257 implants were submitted for sonication. PJI was defined according to the EBJIS criteria as well as according to the International Consensus Meeting criteria of 2018 (ICM 2018). Only cases with at least one corresponding tissue sample were included. Samples were cultured using traditional microbiological plating techniques. Sensitivity and specificity were determined using two-by-two contingency tables. McNemar’s test was used to compare proportions among paired samples. Subgroup analysis was performed dividing the cohort according to the site of PJI, previous antibiotic treatment, and time of manifestation. Prevalence of pathogens was determined for all patients as well as for specific subgroups.ResultsAmong the 257 cases, 145 and 112 were defined as PJI and aseptic failure, respectively. When using the EBJIS criteria, the sensitivity of SFC and PTC was 69.0 and 62.8%, respectively (p = .04). Meanwhile, the specificity was 90.2 and 92.9%, respectively (p = .65). When adopting ICM 2018 criteria, the sensitivity of SFC and PTC was 87.5 and 84.4% (p = .63) respectively, while the specificity was 85.1 and 92.5% (p = .05), respectively. The most commonly identified pathogens were coagulase-negative staphylococci (26% overall), while 31% of PJI were culture-negative and 9% polymicrobial.ConclusionsSFC exhibited significantly greater sensitivity versus PTC when using the EBJIS criteria. Nevertheless, the diagnosis of PJI remains a difficult challenge and different diagnostic tools are necessary to optimize the outcome.

A 65-year-old male suffering from acute spinal cord injury leading to incomplete tetraplegia presented with severe recurrent Clostridium difficile (C. difficile) infection subsequent to antibiotic treatment for pneumonia. After a history of ineffective antimicrobial therapies, including metronidazole, vancomycin, fidaxomicin, rifaximin and tigecycline, leading to several relapses, the patient underwent colonoscopic fecal microbiota transplantation from his healthy son. Four days subsequent to the procedure, the patient showed a systemic inflammation response syndrome. Without detecting an infectious cause, the patient received antimicrobial treatment, including tigecycline, metronidazole, vancomycin via polyethylene glycol and an additional enema for a period of seven days, leading to a prompt recovery and no reported C. difficile infection relapse during a 12 wk follow up.

Background In fracture-related infections (FRI), both the diagnosis of the infection and the identification of the causative pathogen are crucial to optimize treatment outcomes. Sonication has been successfully used for periprosthetic joint infections (PJI); however, its role in FRI remains unknown. Our aim was to determine the diagnostic accuracy (sensitivity, specificity) of sonicate fluid culture (SFC). The primary objective was to compare SFC with peri-implant tissue culture (PTC) overall and among subgroups using the consensus definition by Metsemakers et al. The secondary objective was to determine the yield of SFC in possible fracture-related infections (PFRI). Methods From March 2017 to May 2019, 230 cases of retrieved implants were retrospectively reviewed. To perform sonication, explants were placed in sterile polypropylene jars intraoperatively. After treatment in an ultrasonic bath (Bandelin, Berlin, Germany), sonicate fluid was incubated into blood culture bottles, and conventional culturing was eventually performed. Sensitivity and specificity were determined using two-by-two contingency tables. McNemar’s test was used to compare proportions among paired samples while Fisher’s exact test was used for comparison between categorical variables. Results Of the 230 cases, 107 were identified as FRI, whereas 123 were aseptic revision cases (ARC). Of the latter, 105 were labeled as PFRI. Sensitivity of SFC was higher in comparison with PTC, although this did not reach statistical significance (90.7% vs. 84.1%; p = .065). The specificity of SFC was significantly lower than that of PTC (73.2% vs. 88.6%; p = .003). In PFRI, SFC yielded significantly more positive results than PTC (33/105 vs. 14/105; p = .003). Overall, 142 pathogens were identified by SFC, whereas 131 pathogens were found by PTC. Conclusions We found that sonication of fracture fixation devices may be a useful adjunct in FRI, especially in “low-grade” infections lacking confirmatory clinical criteria. Standardized diagnostic protocols are warranted in order to further optimize the diagnostic accuracy.