The Not-So-Good Prognosis of Streptococcal Periprosthetic Joint Infection Managed by Implant Retention: The Results of a Large Multicenter Study

Background Streptococci are not an infrequent cause of periprostheticjoint infection (PJI). Management by debridement, antibiotics, and implant retention (DAIR) is thought to produce a good prognosis, but little is known about the real likelihood of success. Methods Retrospective, observational, multicenter, international studyperformed during 2003-2012. Eligible patients had a streptococcal PJI that was managed with DAIR. The primary endpoint was failure, defined as death related to infection, relapse/persistence of infection, or the need for salvage therapy. Results Overall, 462 cases were included (median age 72 years, 50% men). The most frequent species was S.agalactiae (34%), and 52% of all cases were hematogenous. Antibiotic treatment was primarily using β- lactams, and 37% of patients received rifampin. Outcomes were evaluable in 444 patients: failure occurred in 187 (42.1%, 95% confidence interval: 37.5%-46.7%) after a median of 62 days from debridement; patients without failure were followed for a median of 802 days. Independent predictors (hazard ratios) of failure were rheumatoid arthritis (2.36), late post- surgical infection(2.20), and bacteremia (1.69). Independent predictors of success were exchange of removable components (0.60), early use of rifampin (0.98 per day of treatment within the first 30 days), and long treatments (≥21 days) with β- lactams, either as monotherapy (0.48) or in combination with rifampin (0.34). Conclusions this is the largest series of streptococcal PJI managed by DAIR, showing a worse prognosis than previously reported. The beneficial effects of exchanging the removable components and of β- lactamsare confirmed, and maybe also a potential benefit from adding rifampin.