Preoperative joint aspiration culture results and causative pathogens in total hip and knee prosthesis infections: mind the gap.

Objectives: In prosthetic joint infections (PJIs), there is no consensus about the utility of the preoperative joint aspiration culture to guide antimicrobial treatment. The main objective of this retrospective study was to investigate the value of these preoperative samples to narrow immediate postoperative empirical antimicrobial treatment in patients with a knee or hip PJI.

Methods: Adult patients admitted for an exchange procedure between June 2007 and July 2016 for whom a preoperative joint aspiration within 6 months prior to the procedure was available and with an antibiotic-free interval before sampling, were eligible. Per PJI, taking both preoperative joint aspiration and intraoperative deep samples into account, causative pathogen(s) were assessed by the current Infectious Diseases Society of America (IDSA) guidelines. Per PJI, agreement of preoperative joint aspiration cultures corresponding to the causative pathogen(s) was investigated both on species and on Gram/fungi level.

Results: From the 85 PJIs, on species level, the total agreement was found in 58 (68%) PJIs. On Gram/fungi level, when preoperative joint aspiration cultures yielded exclusively Gram-positive microorganisms (n = 61), a 100% predictive value for Gram positive causing pathogens was attained. Insufficient predictive value was observed in PJIs with preoperative joint aspiration yielding Gram-negative microorganisms (n = 4), a fungus (n = 1) or with sterile results (n = 19).

Conclusion: In the immediate postoperative setting, the treating team might consider a broad spectrum empirical antibiotic regime, guided by the local epidemiology and susceptibility, which can be narrowed to Gram-positive coverage if preoperative joint aspiration cultures yield exclusively Gram-positive microorganisms.