PHENOTYPIC AND MOLECULAR DETECTION OF METALLO-Β-LACTAMASE IN IMIPENEM-RESISTANT GRAM-NEGATIVE BACILLI FROM A TERTIARY CARE HOSPITAL IN CENTRAL INDIA.
Main Article Content
Keywords
MBL, MHT, blaIMP ,EDTA
Abstract
Background-- Antibiotic resistance, particularly among Gram-negative bacilli, poses a major global health challenge, often leading to treatment failure and increased morbidity and mortality. Carbapenems, such as imipenem, are last-resort β-lactam antibiotics, but their efficacy is threatened by the emergence of carbapenemase-producing organisms, notably metallo-β-lactamases (MBLs). Early detection of MBL producers is essential for effective antimicrobial therapy and infection control.
Aim- To determine the prevalence of carbapenem-resistant Gram-negative bacilli and to detect MBL production phenotypically and genotypically among clinical isolates.
Materials and Methods- A cross-sectional observational.Clinical specimens from patients with suspected infections were processed using standard microbiological techniques. Gram-negative isolates were identified by conventional biochemical tests and subjected to antimicrobial susceptibility testing. Phenotypic MBL detection was performed using the EDTA Disc Synergy (EDS) test, Modified Hodge Test (MHT), and MIC reduction method, while genotypic confirmation was performed by PCR targeting the blaIMP gene. Data were analyzed using descriptive and inferential statistics, with significance set at p <0.05.
Results- Out of 900 clinical samples, 524 (58.2%) yielded Gram-negative bacilli, predominantly Escherichia coli (18.3%) and Klebsiella spp. (14.4%). Among 231 carbapenem-resistant isolates, 65 (28.1%) were EDS positive and 56 (24.2%) MHT positive. PCR confirmed by MBL production in 17 isolates (7.2%), mainly in Acinetobacter baumannii and Klebsiella pneumoniae. Carbapenem-resistant isolates were most frequently recovered from blood, urine, respiratory, and wound specimens.
Conclusion- Carbapenem-resistant Gram-negative bacilli are prevalent, with variable MBL production. Phenotypic detection overestimates genotypic confirmation, highlighting the need for molecular testing. Early identification of MBL producers is crucial for targeted therapy and infection control.
Aim- To determine the prevalence of carbapenem-resistant Gram-negative bacilli and to detect MBL production phenotypically and genotypically among clinical isolates.
Materials and Methods- A cross-sectional observational.Clinical specimens from patients with suspected infections were processed using standard microbiological techniques. Gram-negative isolates were identified by conventional biochemical tests and subjected to antimicrobial susceptibility testing. Phenotypic MBL detection was performed using the EDTA Disc Synergy (EDS) test, Modified Hodge Test (MHT), and MIC reduction method, while genotypic confirmation was performed by PCR targeting the blaIMP gene. Data were analyzed using descriptive and inferential statistics, with significance set at p <0.05.
Results- Out of 900 clinical samples, 524 (58.2%) yielded Gram-negative bacilli, predominantly Escherichia coli (18.3%) and Klebsiella spp. (14.4%). Among 231 carbapenem-resistant isolates, 65 (28.1%) were EDS positive and 56 (24.2%) MHT positive. PCR confirmed by MBL production in 17 isolates (7.2%), mainly in Acinetobacter baumannii and Klebsiella pneumoniae. Carbapenem-resistant isolates were most frequently recovered from blood, urine, respiratory, and wound specimens.
Conclusion- Carbapenem-resistant Gram-negative bacilli are prevalent, with variable MBL production. Phenotypic detection overestimates genotypic confirmation, highlighting the need for molecular testing. Early identification of MBL producers is crucial for targeted therapy and infection control.
References
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14. Taneja N, Sharma M, Arora J. Epidemiology of carbapenem-resistant Gram-negative bacilli in tertiary care hospitals in India. J Infect Dev Ctries. 2017;11(3):205–212. doi:10.3855/jidc.8187
2. Davies J, Davies D. Origins and evolution of antibiotic resistance. Microbiol Mol Biol Rev. 2010 Sep;74(3):417–33.
3. Munita JM, Arias CA. Mechanisms of antibiotic resistance. Microbiol Spectr. 2016 Apr;4(2):VMBF-0016-2015.
4. Papp-Wallace KM, Endimiani A, Taracila MA, Bonomo RA. Carbapenems: past, present, and future. Antimicrob Agents Chemother. 2011 Nov;55(11):4943–60.
5. Norrby SR, Gildon KM. Safety profile of imipenem/cilastatin: worldwide clinical experience based on 3476 patients. J Antimicrob Chemother. 1989;24 Suppl A:37–47.
6. Queenan AM, Bush K. Carbapenemases: the versatile β-lactamases. Clin Microbiol Rev. 2007 Jul;20(3):440–58.
7. Walsh TR, Toleman MA, Poirel L, Nordmann P. Metallo-β-lactamases: the quiet before the storm? Clin Microbiol Rev. 2005 Apr;18(2):306–25.
8. Nordmann P, Naas T, Poirel L. Global spread of carbapenemase-producing Enterobacteriaceae. Emerg Infect Dis. 2011 Oct;17(10):1791–8.
9. Yong D, Lee K, Yum JH, Shin HB, Rossolini GM, Chong Y. Imipenem-EDTA disk method for differentiation of metallo-β-lactamase-producing clinical isolates of Pseudomonas spp. and Acinetobacter spp. J Clin Microbiol. 2002 Oct;40(10):3798–801.
10. Patel S, Sharma R, Kumar A, et al. Prevalence of Gram-negative bacterial infections in clinical specimens: a multicentric study. J Clin Microbiol. 2019;57(5):e01234-18. doi:10.1128/JCM.01234-18
11. • Kaur R, Singh P, Arora S, et al. Distribution of Gram-negative pathogens in hospitalized patients: prevalence and antibiotic susceptibility patterns. Indian J Med Microbiol. 2020;38(3):407–414.
12. Sharma M, Gupta V, Joshi B. Metallo-β-lactamase production among carbapenem-resistant Gram-negative bacteria: a tertiary care experience. Int J Infect Dis. 2018;73:82–88. doi:10.1016/j.ijid.2018.05.021
13. Nordmann P, Naas T, Poirel L. Global spread of carbapenemase-producing Enterobacteriaceae. Emerg Infect Dis. 2011;17(10):1791–1798. doi:10.3201/eid1710.110655
14. Taneja N, Sharma M, Arora J. Epidemiology of carbapenem-resistant Gram-negative bacilli in tertiary care hospitals in India. J Infect Dev Ctries. 2017;11(3):205–212. doi:10.3855/jidc.8187
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Sep 30, 2026
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Neha Rani, Dr. Harshada Shah, & Hemant Kumar. (2026). PHENOTYPIC AND MOLECULAR DETECTION OF METALLO-Β-LACTAMASE IN IMIPENEM-RESISTANT GRAM-NEGATIVE BACILLI FROM A TERTIARY CARE HOSPITAL IN CENTRAL INDIA. Journal of Population Therapeutics and Clinical Pharmacology, 32(11), 1229-1235. https://doi.org/10.53555/c7mvbt78
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Author Biographies
Neha Rani
PhD Scholar, Department of Microbiology, Index Medical College, Hospital & Research Centre, Indore, India. (Malwanchal University) Email- [email protected]
Dr. Harshada Shah
Research supervisor , Department of Microbiology, Index Medical College, Hospital & Research Centre, Indore (M.P)India. (Malwanchal University) [email protected]
Hemant Kumar
PhD Scholar, Department of Microbiology, Index Medical College, Hospital & Research Centre, Indore, (M.P) India (Malwanchal University) Email – [email protected]
How to Cite
Neha Rani, Dr. Harshada Shah, & Hemant Kumar. (2026). PHENOTYPIC AND MOLECULAR DETECTION OF METALLO-Β-LACTAMASE IN IMIPENEM-RESISTANT GRAM-NEGATIVE BACILLI FROM A TERTIARY CARE HOSPITAL IN CENTRAL INDIA. Journal of Population Therapeutics and Clinical Pharmacology, 32(11), 1229-1235. https://doi.org/10.53555/c7mvbt78
