Sonication cultures of explanted components as an add-on test to routinely conducted microbiological diagnostics improve pathogen detection.

The purpose of this study was to improve the pathogen detection in prosthetic joint infections, particularly to evaluate the feasibility of the sonication culture method in the clinical routine. Explanted components of all patients with presumptive prosthetic or implant infection were sonicated separately in sterile containers to dislodge the adherent bacteria from the surfaces and cultured. The results of sonication culture were compared to the conventional tissue culture. We investigated 60 consecutive patients with loosening of the prostheses or implants Forty patients had septic and 20 aseptic loosening (24 knee prostheses, 21 hip prostheses, 6 mega-prostheses, 2 shoulder prostheses, 6 osteosynthesis, 1 spinal instrumentation). The sensitivity of sonication fluid culture was 83.3%, of single positive tissue culture was 72.2% and 61.1% when two or more cultures yielded the same microorganism. In patients receiving antibiotic therapy the sensitivity was 65.9%, 57.5%, and 42.5%, respectively. Pathogens detected in a single tissue culture as well as in sonication culture yielded a significantly higher rate of prosthetic infection than conventional tissue culture alone (p = 0.008), even in patients receiving continuous antibiotic therapy before explantation (p = 0.016). The sonication method represents an essential add-on in pathogen detection compared to conventional tissue culture.