Optimal duration of antimicrobial regimen after reimplantation of two-stage procedures for periprosthetic joint infection (PJI) is poorly standardized. The aim of this study was to assess the characteristics of reimplantation microbiology with 6 weeks (2nd stage positive culture) or 10 days (2nd stage negative culture) of antibiotics in patients with complex chronic PJI and factors associated with microbiology at reimplantation.

We performed a retrospective single-center study including all consecutive complex PJI recipients managed by two-stage surgery in a referral centre, from 2015 to 2018. Outcome was assessed at a minimum 2-year follow-up. Logistic regression analysis was performed to assess predictors of reimplantation microbiology.

Fifty patients (median age 69 [62–77] years) were included. PJI predominantly involved the hip (48%). The most common microorganisms were Staphylococcus aureus (36%), and coagulase-negative staphylococci (24%). At the second stage, reimplantation microbiology was positive for 10 patients (20%). Documentation was obtained within 48hours. With median follow-up of 41 [30–50] months after reimplantation, treatment failure occurred in 4 patients (8%). Using log-rank to compare Kaplan–Meier survival curves, no difference in the probability of treatment failure was found according to reimplantation microbiology (P=0.34). After adjustment, relapse was not associated with positive reimplantation microbiology (P=0.53).

In this work, positive microbiology at reimplantation did not predict treatment failure. Rapid growth at post-reimplantation suggests that antibiotic use should not exceed 10 days when cultures are negative. Additional studies are needed to determine the optimal duration of antibiotic therapy in case of negative microbiology.