DETECTION OF CARBAPENEM RESISTANCE AND METALLO-Β-LACTAMASE PRODUCTION AMONG GRAM-NEGATIVE BACTERIAL ISOLATES IN A TERTIARY CARE CENTRE.
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Keywords
GNB, MBL, NDM, mCIM, OXA-48 carbapenemase, antimicrobial resistance
Abstract
Background:
Carbapenem-resistant Gram-negative bacteria have emerged as a major global health threat due to their association with limited treatment options and increased morbidity and mortality. Among the various resistance mechanisms, metallo-β-lactamase (MBL) production plays a significant role in mediating resistance to carbapenem antibiotics. Continuous monitoring of resistance patterns is therefore essential to guide appropriate therapeutic decisions and infection control strategies.
Objectives: To determine the prevalence of carbapenem resistance and metallo-β-lactamase production among Gram-negative bacterial isolates and to evaluate the distribution of carbapenemase types in a tertiary care hospital setting.
Materials and Methods: This cross-sectional study included 334 Gram-negative bacterial isolates obtained from clinical specimens. Carbapenem resistance was screened using the modified carbapenem inactivation method (mCIM). Detection of MBL production was carried out using the Double Disc Synergy Test (DDST) and confirmed by the E-test. Carbapenemase production was further evaluated using the CARBA NP test. Statistical analysis was performed to assess associations between resistance patterns and bacterial species.
Results: Out of 334 isolates, 143 (42.8%) were found to be carbapenem-resistant, while 191 (57.2%) were carbapenem-sensitive. Among the carbapenem-resistant isolates, 67 (44.6%) were identified as MBL producers. No significant difference was observed between the DDST and E-test methods for detecting MBL production (p = 1.000). The predominant carbapenemase detected was NDM among Escherichia coli, whereas OXA-48 was more commonly detected among Klebsiella pneumoniae and Pseudomonas aeruginosa. A statistically significant association was observed between bacterial species and carbapenemase production (p < 0.01).
Conclusion: The study demonstrates a high prevalence of carbapenem-resistant Gram-negative bacteria, with a considerable proportion of isolates producing metallo-β-lactamase enzymes. Early detection of resistant organisms using reliable phenotypic methods, along with strengthened antimicrobial stewardship and infection control practices, is essential to limit the spread of multidrug-resistant pathogens in healthcare settings.
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Neha Singh
Research Scholar, Department of Microbiology, IMCH&RC, Indore, India.
Munesh Kumar Sharma
Professor, Department of Microbiology, Amaltas Institute of Medical College, Dewas, India.
