Detection of antibiotic resistance genes from blood cultures: performance assessment and potential impact on antibiotic therapy management.

Molecular assays may constitute a valid method to timely predict antimicrobial resistance and optimize empirical antibiotic therapies. We assessed ELITe MGB® assays in blood culture workflow to detect main carbapenemase and ESBL genes, Staphylococcus aureus and mec genes in less than 3h. Excellent agreement results between genotypic and conventional phenotypic approaches were obtained. Retrospective analysis of medical records revealed that approximately 50% of bloodstream infections caused by ESBL-producing Enterobacteriaceae, carbapenemase-producing Enterobacteriaceae, or MRSA were initially treated with inactive drugs. Overall, 36.3% of patients could have been treated with appropriate therapy almost 24h early if molecular data had been used.