Frank BJH, Aichmair A, Simon S, et al. - In the treatment of periprosthetic joint infections, a positive microbiological result at reimplantation may result in a failed 2-stage revision arthroplasty. Researchers here examined culture positive first and second stage procedures in revision knee and hip arthroplasty with respect to the changes in microbiological spectrum and resistance pattern. A total of 327 two-stage revision arthroplasties on 312 patients were performed between January 2011 and December 2019. A positive microbiological culture was observed in 37 of 312 (11.9%) patients (20 hips/17 knees) during the first and second stage procedure. Fifteen of 37 of patients (40.5%) with culture positive first and second stage procedures required re-revision at a median follow-up of 3.5 years. Microbiological changes were observed in 83.8% (31/37) of patients between the first and second stage and in 88.9% (8/9) between the second stage and subsequent culture positive re-revision. Findings overall suggest common occurrence of changes in microbiological spectrum and resistance pattern between culture positive first and second stage procedures as well as subsequent re-revisions. Researchers suggest considering this in the antimicrobial treatment of periprosthetic joint infections.