Problems in the approach to infected total prostheses and microbiological diagnostic of infected prostheses - sonication
Abstract
Replacement of total joint prosthesis is a traditional choice in management therapy of aseptic and septic loosening of implants. The preconditions for success include a high-level experience of the orthopaedic surgeon, the isolation of pathogens, and the pattern chosen for postoperative antibiotic therapy.
The standard culture technique could be often moderately sensitive, because bacteria colonising the surface of implants grow predominantly in adherent biofilms. The authors strived to improve the isolation of bacteria from the removed hip prosthesis by means of sonication.
Methods and material: From March 2001 to November 2005 the authors retrieved 170 hip prostheses from patients at revision operations for aseptic loosening (97) or septic loosening (73) of implants. The femoral and acetabular components after sonication and tissue contact with the implants after homogenisation in Ringer solution were cultivated aerobically and anaerobically.
The routine specimens, swabs and aspirates of joint fluid were cultivated aerobically and anaerobically simultaneously. The isolated organisms were identified and sensitivity to antibiotics was tested by standard laboratory methods.
Results and discussion: 43.3% of cultures of the aseptic loosening were positive. Positive were 42.3% of components, 17.5% of tissue specimens, and 7.2% of routine specimens. 80.8% of cultures from septic loosening were positive.
Positive were 71.2% of components, 60.3% of tissue specimens, and 43% of routine specimens. Conclusions: The authors believe that the sonication method may increase the detection of an infection in the total hip replacement, because sonication increases sensitivity of the culture technique by releasing bacteria from the biofilm, which were not isolated by the routine culture technique.