PROGNOSTIC FACTORS OF STREPTOCOCCAL PROSTHETIC BONE AND JOINT INFECTIONS MANAGED IN REFERENCE CENTRES

Aim The optimal treatment of streptococcal prosthetic joint infections (PJIs) is unclear. Poorer outcome has been associated with Streptococcus agalactiae species, comorbidities and polyethylene exchange for conservative approach. Rifampicin use may be associated with higher remission rate but results are sparse. Method A cohort of streptococcal PJI (including total hip arthroplasty –THA- or total knee arthroplasty –TKA-) was prospectively created and retrospectively reviewed in 7 reference centers for management of complex PJI between January 1, 2010 and December 31, 2012. Results Seventy patients (47 infections of THA and 23 infections of total TKA) with monomicrobial infections were included. Median age was 77 (interquartile range [IQR] [69 – 83], 15.6% (n=11) had diabetes, median Charlson comorbidity score was 4 [3 – 6] and 31.4% (n=22) had chronic heart failure. Streptococcus agalactiae and S. dysgalactiae were the most commonly streptococcal species found, in 38.6% (n=27) and 17.1% (n=12) of cases respectively. Debridement, antibiotic and implant retention (DAIR) was performed after a median time of 7 days [3 – 8] with polyethylene exchange (PE) performed in 21% of these treatments. After a median follow-up of 22 month [12 – 31], 27% of patients relapsed corresponding to 51.4% of DAIR treatment and 0% of one- (n=15) or two-stage exchange strategy (n=17). Rifampicin or levofloxacin combination were not associated with a better outcome (p=0.82 and p=1, respectively). A shorter intravenous antimicrobial therapy, a S. agalactiae species and DAIR treatment were associated with a higher risk of failure. In multivariate analysis, only DAIR treatment and S. agalactiae were independent factors of relapse. PE was associated with a trend toward benefit (odds ratio 0.26 [95% CI: 0.021 – 1.98; p=0.26]) but did not reach statistical significance. Conclusions Streptococcal PJIs managed with DAIR have a poor prognosis and S. agalactiae seems to be an independent factor of failure.