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Diagnosis of periprosthetic joint infection using multiplex PCR in sonication fluid of removed implants

Abstract number: P1828

Achermann Y., Vogt M., Leunig M., Hermann H., Wüst J., Trampuz A.

Objectives: The microbiological diagnosis of periprosthetic joint infection (PJI) is crucial for successful outcome. Cultures have limited sensitivity, especially in patients receiving previous antimicrobial treatment. We compared the multiplex real-time PCR test (SeptiFast, Roche Diagnostics) for detection of microbial DNA with cultures of sonication fluid.

Methods: We prospectively included patients in whom an infected prosthesis (or part of it) was removed from 8/08 through 12/08. PJI was defined as visible purulence, acute inflammation on histopathology, sinus tract or microbial growth in periprosthetic tissue (at least 2 positive tissues were required for low-virulent organisms). The removed implant was sonicated (described in NEJM 2007;357:654) and the resulting sonication fluid was cultured aerobically and anaerobically. In addition, 1 ml of the fluid was investigated using SeptiFast.

Results: In this ongoing study, 21 episodes of PJI in 18 patients were included (median age 75 y; range 49–86 y), including hip (n = 9), knee (n = 9), shoulder (n = 2) and ankle prosthesis (n = 1). The following pathogens were cultured: Staphylococcus aureus (n = 3), coagulase-negative staphylococci (n = 6), streptococcus agalactiae(n = 1), Propionibacterium acnes (n = 2) and mixed infection (n = 3). In sonication culture, the causative organism was identified in 14 (67%) cases and by SeptiFast PCR in 18 (86%) cases. In 7 false-negative cultures, the pathogen was identified only by SeptiFast (4 S. aureus, 1 coagulase-negative staphylococcus, 1 streptococcus sp.) or an additional microorganism was found with the SeptiFast (Klebsiella oxytoca/pneumoniae). In all 3 false-negative cases by SeptiFast, P. acnes was missed. All patients with false-negative cultures received previous antibiotic therapy. Among 11 cases receiving antibiotics for a median of 16 d (range 3–60 d) before the diagnostic procedure, SeptiFast was positive in all 11 (100%), whereas sonication cultures grew the organism in only 4 (36%).

Conclusions: SeptiFast in sonication fluid has a higher sensitivity for diagnosis of PJI compared to sonication culture (86% vs 67%), particularly among patients receiving previous antibiotic therapy (100% vs 36%). All missed organisms by SeptiFast were P. acnes, which can not be detected due to lack of specific primers in the PCR kit. With modified primer sets, multiplex PCR has the potential for further improvement of the diagnosis of PJI, particularly in patients receiving antibiotics.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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