International Journal of Multidisciplinary Health Sciences and Research

Category: Original Article,      DOI: Recived: 12/02/2024, Accepted: 24/03/2024, Published online: 29/03/2024

Comparison of Phenotypic and Genotypic Methods for Detection of Extended-Spectrum Beta-Lactamases in Enterobacteriales

Simmi Singh1 , Priyanka Raikwar2 , Mansi Srivastava3 , Suneet Yadav4*

Abstract:

Background: Extended-spectrum beta-lactamases (ESBLs) in Enterobacteriales pose significant clinical challenges. This study aimed to compare phenotypic and genotypic methods for ESBL detection in clinical isolates. Methods: A cross-sectional study was conducted on 500 non-duplicate Enterobacteriales isolates. Phenotypic methods including double-disk synergy test (DDST), combination disk test (CDT), and ESBL E-test were compared with genotypic methods (multiplex PCR and real-time PCR). Wholegenome sequencing was performed on a subset of isolates. Sensitivity, specificity, and concordance between methods were assessed. Results: Biofilm formation was observed in 85% of isolates, with 20% classified as strong producers. Strong biofilm formation was significantly associated with increased resistance to carbapenems (OR 3.5, p<0.001) and ceftazidime (OR 3.2, p<0.001). The algD gene was most prevalent (90%) among biofilm-associated genes. MBEC values were consistently 64-fold higher than MIC values for all tested antibiotics. Efflux pump inhibition resulted in a ?4-fold MIC reduction in 70% of isolates for ciprofloxacin. Conclusion: Both phenotypic and genotypic methods demonstrated high accuracy in ESBL detection. The ESBL E-test showed the highest sensitivity and specificity. CTX-M-type ESBLs, particularly group 1, were predominant. The high concordance between methods supports the continued use of phenotypic tests in clinical laboratories, with molecular methods providing valuable additional information for epidemiological studies and infection control.