Evaluation of Combination Antimicrobial Therapy Against Extended-Spectrum Beta-Lactamase Producing Enterobacterales: An In Vitro Study

Abstract

Background: Extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales pose a significant therapeutic challenge due to multidrug resistance.Objectives: To evaluate the in vitro efficacy of selected antimicrobial combinations against ESBL-producing Enterobacterales. Materials and Methods: Clinically significant ESBL-producing isolates were identified using standard microbiological methods and confirmed by the combination disc method. Antimicrobial combinations were assessed using the checkerboard assay, and interactions were interpreted based on the Fractional Inhibitory Concentration Index (FICI).Results: Among the tested combinations, meropenem–amikacin demonstrated the highest synergistic activity, followed by piperacillin–tazobactam–amikacin, while most other combinations showed additive or indifferent effects. No antagonistic interactions were observed. Conclusion: Selected antimicrobial combinations exhibited promising in vitro synergistic activity against ESBL-producing Enterobacterales. These findings support further clinical evaluation of combination therapy as a potential strategy for managing infections caused by multidrug-resistant organisms