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

Molecular assays may constitute a valid method for timely prediction of antimicrobial resistance and optimization of empirical antibiotic therapies. This study assessed ELITe MGB assays of blood cultures to detect the main carbapenemase and extended-spectrum beta-lactamase (ESBL) genes, Staphylococcus aureus and mec genes in less than 3 h. Excellent agreement was found between the results of genotypic and conventional phenotypic approaches. Retrospective analysis of medical records revealed that approximately 50% of bloodstream infections caused by ESBL-producing Enterobacteriaceae, carbapenemase-producing Enterobacteriaceae or meticillin-resistant S. aureus were initially treated with inactive drugs. Overall, 36.3% of patients could have been treated with appropriate therapy at least 24 h earlier if molecular data had been used.