Abstract
Aim
S. aureus and coagulase-negative staphylococci are the most frequent bacteria responsible for PJI. In patients with acute PJI (i.e. <1 month following the implantation), DAIR with exchange of removal components followed by a combination of antibiotics that includes rifampin (particularly rifampin+fluoroquinolone) are recommended. Unfortunately, some patients could not receive rifampin due to drug-drug interaction or stopped it due to an adverse event. Finally, it was unclear if the dose and the duration of rifampin influenced the prognosis.
Method
We performed a retrospective cohort study in 4 hospitals and included patients with staphylococcal acute post-operative (< 1 month) PJI treated with DAIR in 2011–2016 period. Univariate and multivariate Cox analysis and Kaplan Meier curves were used to determine the risk factors for treatment failure (persistence of clinical signs, new surgery w/o persistence or superinfection, infection-related death).
Results
79 patients were included (median age: 71 years IQR 53–89]; 55 men [69.6 %]; median ASA score: 2 [IQR 2–3]). Bacterial cultures revealed 65 S. aureus (82.3 %) and 15 coagulase-negative staphylococci (19.0 %) infections, including 14 methicillin-resistant isolates (17.7 %). Among all isolates, only 2 (2.5 %) were resistant to rifampin and 16 (20.3 %) were resistant to fluoroquinolone. The median duration of antimicrobial therapy was 92 days (IQR 31–152). Only 59 patients received rifampin (74.7 %), and 35 (44.3 %) the combination rifampin + fluoroquinolone. Median duration of rifampin was 56.5 days (IQR 15.8–86.0) and median dose 14.6mg/kg/d (IQR 13.0–16.7). Forty patients (50.6 %) received rifampin in the first 2 weeks and 43 patients (54.4 %) received at least 2 weeks of rifampin. Six patients (7.6 %) developed an adverse event leading to rifampin interruption. During a median follow-up of 443 days (IQR 219.5–790.5), 21 patients (26.6 %) experienced a treatment failure including 12 persistence of the initial pathogen (57.1 %) and 9 superinfections (42.9 %). An ASA score >2 (HR 2.8; 95%CI 1.26–6.15), the use of rifampin (HR 0.4; 95% CI 0.17–0.95) and the duration of rifampin treatment (HR 0.83; 95%CI 0.75–0.92 per additional week of treatment) were significant determinants of the outcome (but not methicillin-resistance). Receiving >2 weeks of rifampin prevented the failure, but an introduction during the first 2 weeks did not influence the outcome.
Conclusions
In patients with staphylococcal acute PJI, the use of rifampin and its duration strongly influenced the prognosis. As 25% of patients could not receive rifampin, new drugs with anti-biofilm activity are required.
