SYSTEMATIC REVIEW OF LABORATORY-BASED METHODS FOR DETECTING EXTENDED-SPECTRUM BETA-LACTAMASE (ESBL)-PRODUCING ENTEROBACTERIACEAE

Abstract Rapid and accurate laboratory detection of extended spectrum β lactamase (ESBL) producing Enterobacteriaceae is essential for antimicrobial stewardship and infection control. We systematically reviewed phenotypic and genotypic laboratory methods and rapid assays for ESBL detection across clinical specimens and isolates. Searches identified 12 original studies evaluating chromogenic media, confirmatory disc, Etest approaches, automated systems, MALDI-TOF hydrolysis assays, and lateral-flow immunoassays (LFIA) for CTX-M enzymes. Across chromogenic media, sensitivity typically exceeded 85-95% with notable gains after selective pre-enrichment, albeit at a trade-off in specificity. Combination disc tests and ESBL-Etest configurations performed well, especially when cefepime-clavulanate was incorporated, which improved detection in Enterobacter spp. Automated platforms (Vitek 2) achieved rapid, high agreement versus reference standards in large series. MALDI-TOF-based β-lactam hydrolysis and CTX-M LFIAs provided actionable same-shift results directly from positive blood culture fluid or colonies, facilitating earlier targeted therapy. However, co-production of AmpC or K1 β-lactamases and species-specific traits can mask ESBL phenotypes, underscoring the need for method combinations or reflex molecular testing in selected contexts. Overall, an algorithm that integrates selective culture (with pre-enrichment where appropriate), a clavulanate-based confirmatory test, and a rapid ESBL, CTX-M assay yields timely, reliable detection to inform clinical and infection-prevention decisions.