Evaluation of the HB&L system for the culture of prosthetic and osteoarticular origin samples

Prosthetic and osteoarticular infections represent a complex condition to diagnose and resolve. In both cases, the eradication of microorganisms is difficult because of anatomical and physiological characteristics of the site of infection (bone).The best strategy for an effective pharmacological treatment is based on an early diagnosis confirmed by microbiological testing of bone, periprosthetic tissue or removed prostheses, to support clinicians to undertake prolonged targeted therapy. The purpose of this paper is to assess the clinical correlation between the results of the cultures performed with automated HB&L (ALIFAX) system compared to the result of traditional methods. HB&L is a system to perform bacterial cultures, susceptibility and direct P.A.R. tests on biological materials based on detection of bacteria and fungi by laser light-scattering kinetics in liquid culture medium at 37°C. Samples get to laboratory are inoculated in rich broth and placed in the incubator. The next day are processed accordin to the following protocol: 500 ml of the broth are transferred in the vial of the instrument and 200 ml of supplement DEB for fastidious organisms are added.The cultures are incubated for 360 minutes in the same time PAR test (antimicrobial residual power) is determined. In the first half of 2009 418 samples collected from prostheses and osteoarticular infections from 118 patients were analyzed.The tests showed 304 negative and 114 positive samples (27.30%) from which were isolated Gram negative (17.5%) and Gram positive (82.5%) bacteria. Gram positive included 38.3% S. aureus, 33% coagulase negative Staphylococci and 26.6% Enterococci. Preliminary data obtained by the HB&L system for the culture of tissue sample, as well as the improvement of surgical techniques have led to a significant increase in correlation with the clinical data compared to traditional microbiological analysis.