Recurrent periprosthetic joint infection: persistent or new infection?

It is unclear if recurrent periprosthetic joint infection (PJI) is a result of failed pathogen eradication. This study addresses this issue. We identified 92 patients from three institutions who failed two-stage exchange. Cultured organisms at each stage of treatment were compared to determine whether these were persistent or new infections. Only twenty-nine of the 92 patients (31.5%) had identical organisms at treatment failure. Of the failures associated with Staphylococcus as the original infecting organism, 37% (25 of 67) failed due to the same organism compared to only 16% (four of 25) caused by other organisms. Positive cultures at reimplantation and poor health status were associated with higher rates of recurrent infection due to new organisms. Successful management of PJI with a two-stage exchange must stress minimization of comorbid risk factors that may contribute to the low success rate of PJI treatment and recurrence of infection.