First evaluation of the automated-multiplex-PCR Unyvero ITI G2 cartridge for rapid diagnosis of osteo-articular infections.

ABSTRACT

OBJECTIVE: Conventional microbiological methods (CMM), including long-term culture, for the diagnosis of osteo-articular infections (OAI) fail in at least 5% of all cases. Only one IOA dedicated molecular method has been commercialized, and only the first version of this kit has been studied. The aim of this work was to evaluate the concordance between test results obtained with the second version of the Unyvero ITI G2 cartridge (Curetis) and CMM. The cartridge, combining one-step automated lysis/DNA extraction with multiplex PCR and amplicon detection by array hybridization, allows for the detection of 102 prevalent pathogens and their antibiotic resistance markers directly in clinical specimens (liquid [n=8] or solid [n=32]). MATERIAL AND METHODS: Frozen samples from 40 patients who underwent orthopedic surgery at Pitié-Salpêtrière hospital were tested retrospectively with the cartridge 5 were culture-negative, 25 revealed monomicrobial and 10 polymicrobial OAI. The 2 main surgical sites were hip (22.5%) and knee (17.5%). RESULTS: Extraction, amplification and hybridization reactions were completed in 28 of the 40 cases, failed in all cartridge chambers in 6 cases, and in 1 or 2 chambers in an additional 6 cases. Overall sensitivity and specificity for microorganism identification were estimated at 67.6% and 98.2%, when complete and partial failures were excluded. CONCLUSIONS: These results show that the performances of the second version of the Unyvero ITI G2 cartridge should be further enhanced before considering avoiding conventional microbiological methods.