Microbiological Epidemiology Depending on Time to Occurrence of Prosthetic Joint Infection (PJI): Impact on the Empirical Antimicrobial Strategies

BACKGROUND: Empirical antimicrobial therapy of prosthetic-joint infection (PJI) is a major clinical challenge and current guidelines recommend the combination of vancomycin plus a broad-spectrum β-lactamin. As Gram-negative bacilli (GNB) are probably less represented in late infections, we evaluate the microbiological epidemiology in patients with PJI according to the chronology of infection. METHODS: All patients managed in a reference center for complex bone and joint infections in France (2011 and 2016) were included in a prospective cohort study. Microbiological data at the time of diagnosis were collected and analyzed according to the chronology of infection. RESULTS: We included 567 PJI (284 males, 50.1%; median age 70.3 years). The median occurrence time was 23.4 weeks after prosthesis implantation (285 hip and 255 knee PJI, which were revision prosthesis in 216 [40.3%] cases). Microbiological bone samples found 164 [28.9%] S. aureus (including 26 [16.3%] MRSA), 162 [28.6%] coagulase-negative Staphylococci (CoNS, including 80 [58.8%] methicillin-resistant CoNS), 80 (14.1%) Enterobacteriaceae, 74 (13.1%) Streptococci, and 85 (15.0%) anaerobes (including 60 [10.6%] Propionibacterium). Infection was plurimicrobial in 10 [18.2%] cases. Among the 183 patients (32%) with late PJI (occurring >1 year), obtained after exclusion of the 59 patients (10.4%) with hematogenous origins, Enterobacteriacecae (n = 8; 4.4%; P < 10(–3)) were much less represented than in patients with early PJI occurring <1 year. No difference was observed regarding the the presence of non-fermenting GNB, with a prevalence of 4.6 and 2.7% in early and late PJI, respectively. Taken together, these data suggest that a broad-spectrum β-lactam antibiotic might be useful in only 12 (6.6%) patients with late PJI, compared with 66 (20.3%) patients with early PJI (P < 10(–3)). Of note, there were statistically more anaerobes (n = 40; 21.9%) in late PJI, including 32 Propionibacterium (17.5%; P < 10(–3)). CONCLUSION: Considering the minority amount of GNB in late post-operative PJI and the overrepresentation of anaerobes including P. acnes, the empirical treatment should be reconsidered, especially when a two-stage exchange is planned. In those situations, another acceptable option could be the vancomycin+clindamycin combination. DISCLOSURES: T. Ferry, HERAEUS: Consultant, Speaker honorarium. S. Lustig, Heraeus: Consultant, Consulting fee.