Screening of Multidrug-Resistant Bacteria Against β-Lactams Group of Antibiotics

Abstract

The emergence of multidrug-resistant (MDR) bacteria has become a major challenge in the effective management of nosocomial infections. The present study focused on the isolation and identification of MDR bacteria collected from the various hospital environments, including surgical ward, maternity unit, toilet, and clinical waste materials. A total of 23 bacterial isolates were obtained from the mix culture as a pure culture. Morphological and biochemical characterization, including IMViC, catalase, and carbohydrate fermentation tests were performed for putative identification of the isolates.  Screening was done against selected standard β-lactam antibiotics, including Ampicillin (AMP, 10 µg), Ertapenem (ETP, 10 µg), Cefoxitin (CX, 30 µg), Cefixime (CFM, 5 µg), Ceftriaxone (CTR, 10 µg), Faropenem (FRP, 10 µg), Cefuroxime (CXM, 30 µg), Aztreonam (AT, 30 µg), and Amoxicillin-Clavulanic acid (AMC, 30 µg). Antibiotic susceptibility profiling was carried out using the Kirby-Bauer disc diffusion and agar well diffusion methods, which revealed that the majority of the isolates exhibited high levels of resistance to multiple generations of β-lactam antibiotics. Among the 23 isolates, 09 bacterial isolates demonstrated 100% resistance to Amoxicillin, Cefuroxime, Faropenem, and Aztreonam. Furthermore, combination studies employing different antibiotic ratios (1:1, 1:3, and 3:1) failed to enhance antibacterial activity, indicating limited therapeutic effectiveness of these combinations. These findings highlight the widespread occurrence of MDR bacteria in hospital environments and emphasize the urgent need for alternative antimicrobial strategies to combat nosocomial infections.