Improved identification of polymicrobial infection in total knee arthroplasty through sonicate fluid cultures.
BACKGROUND
Periprosthetic joint infection (PJI) is the leading cause for early failure of total knee arthroplasty (TKA). An insufficient diagnosis of the involved bacterial species can be a possible cause for this high failure rate. Sonicate fluid cultures (SFC) have been shown to increase the detection rate of PJI in comparison to the use of conventional microbiological methods. The hypothesis of this study is that sonication will improve not only the detection rate of PJI, but also the detection rate of polymicrobial infection in patients with TKA revision surgery.


METHODS
109 patients, undergoing TKA revision surgery, were enrolled in this prospective cohort study and received a synovial aspiration, intraoperative tissue cultures, histological sampling of the periprosthetic membrane (PM), and sonication of the explanted endoprosthesis. A PJI was defined according to the following criteria: presence of intraarticular pus or a sinus tract, positive isolation of the same bacterial species in ≥2 microbiological samples or a PM indicative of infection.


RESULTS
31 patients had a defined PJI according to the above-mentioned criteria. SFC achieved the highest sensitivity (74 %) of all microbiological methods. The PM achieved a sensitivity of 87 %. When the results of the SFC and the PM were combined, it was possible to further increase the sensitivity to 94 %. The utilization of SFC doubled the number of polymicrobial bacterial isolations in our patient collective. There were 12 cases of polymicrobial bacterial isolations, six were detectable through conventional microbiological methods, four were detectable through SFC and two were identifiable as polymicrobial through the isolation of an additional bacterial species in the SFC.


CONCLUSIONS
In our study, SFC were the most sensitive microbiological method and were surpassed only by the histology. The use of SFC doubled the detection rate of polymicrobial isolations, which would be missed with conventional microbiological methods alone.
Orthopaedic Department, Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany. Viktor.Janz@Charite.de.
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Janz
Orthopaedic Department, Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
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Wassilew
Department for Trauma, Hand and Reconstruction Surgery, Universitätsklinikum Jena, Erlanger Allee 101, 07749, Jena, Germany.
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Kribus
Orthopaedic Department, Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
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Trampuz
Orthopaedic Department, Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
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Perka
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D001419:Bacteria / Q000302:isolation & purification*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000382:microbiology; D015203:Reproducibility of Results; D013010:Sonication / Q000379:methods*
Polymicrobial periprosthetic joint infection (PJI); Sonication; TKA