Silent Synergy: Is the Presence of Concurrent β-Lactamase Mechanisms Undermining Antimicrobial Effectiveness?

Background The worldwide escalation of antimicrobial resistance poses a substantial challenge to the effective management of both community-acquired and hospital-associated infections. Among Gram-negative bacteria, resistance to β-lactam antibiotics is predominantly mediated by enzymes such as extended-spectrum β-lactamases, AmpC β-lactamases, and metallo-β-lactamases. Aim This study aimed to identify the concurrent production of these β-lactamase mechanisms in Gram-negative clinical isolates. Materials and methods A cross-sectional laboratory-based study was performed on 185 non-duplicate Enterobacteriaceae isolates obtained from clinical specimens. All the isolates underwent phenotypic screening for extended spectrum of β-lactamases (ESBL), AmpC, and metallo-β-lactamases (MBL) production using standard disk diffusion-based methods. The study adhered to ethical guidelines with institutional approval. Data were analyzed statistically using the Chi-square test, with significance set at p < 0.05. Results Out of 185 Enterobacteriaceae isolates, Klebsiella pneumoniae (90; 50.0%) and Escherichia coli (60; 33.3%) were the most prevalent. The maximum number of isolates was observed in males aged 41-60 years and females aged 21-40 years. Of 145 MDR isolates, 63 (43.4%) co-expressed two or three β-lactamases, with 28 (19.3%) showing MBL + ESBL, 13 (8.9%) MBL + AmpC, 16 (11%) ESBL + AmpC, and 6 (4.1%) concurrently producing MBL, ESBL, and AmpC. Conclusion Over the course of the study, this investigation demonstrated the substantial burden of multidrug-resistant Enterobacteriaceae, with 63 (43.4%) isolates co-expressing multiple β-lactamases and 6 (4.1%) simultaneously producing MBL, ESBL, and AmpC, highlighting a critical challenge. Incorporating routine screening for these enzymes is essential to manage infection and limit the spread of resistance.