Evaluation of 3 different agar media for rapid detection of extended-spectrum β-lactamase-producing Enterobacteriaceae from surveillance samples

Abstract

Rapid detection of extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacilli in surveillance samples of high-risk patients allows early optimization of antimicrobial therapy and timely introduction of infection control procedures. This study evaluated the BLSE (AES Chemunex), chromID ESBL (bioMérieux), and Brilliance ESBL agar (Oxoid) for rapid detection of ESBL-producing Enterobacteriaceae from surveillance samples. A total of 139 perineal and nose samples were processed. Isolated bacterial strains were identified by mass spectrometry. ESBL confirmation was performed by phenotypical and molecular tests. Overall, 16 ESBL-producing Enterobacteriaceae were recovered. The sensitivities after 24 h of incubation were comparable (BLSE, 87.5%; Brilliance ESBL, 87.5%; and chromID, 81.3%). The specificity of chromogenic media (80.7-82.1%) was significantly higher compared to BLSE (60.8%). All 3 media are reliable to screen for ESBL-producing Enterobacteriaceae from surveillance samples. Yet, the main advantages of chromogenic media over BLSE reside in their chromogenic character and higher specificity, reducing the total number of isolates that require further identification and ESBL confirmation testing.