Occurrence of Metallo-β-Lactamase Among Gram-Negative Bacilli In A Tertiary Care Hospital and Their Antibiogram Patterns

Metallo-beta-lactamases (MBLs) are enzymes that confer resistance to a broad spectrum of beta-lactam antibiotics, including carbapenems, which are often considered the last line of defense against multidrug-resistant bacterial infections. The emergence of MBL-producing bacteria has significantly compromised treatment options, particularly for Gram-negative pathogens, which are increasingly resistant worldwide. This study investigates the prevalence of MBL-producing Gram-negative bacilli in a tertiary care hospital in India, aiming to provide insights into their distribution and resistance patterns. A total of 150 Gram-negative bacterial isolates were obtained from various clinical specimens, including urine, pus, blood, sputum, and stool. Antimicrobial susceptibility was assessed using the Kirby-Bauer disc diffusion method. MBL production was detected using the imipenem-EDTA combined disk test and the double disk synergy test. Among the isolates, Escherichia coli was the most frequently identified organism (50%), followed by Klebsiella spp. (20.66%) and Pseudomonas aeruginosa (10%). While 82.22% of isolates remained sensitive to imipenem, resistance to ampicillin was the highest (85.9%). MBL production was confirmed in 30 isolates, with a positivity rate of 63.33% using the combined disk test. The notable prevalence of MBL-producing Gram-negative bacilli underscores a serious challenge in antimicrobial therapy. These findings emphasize the urgent need for ongoing surveillance, robust infection control strategies, and prudent antibiotic stewardship in healthcare settings to curb the spread of multidrug-resistant organisms.