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. 2025 Sep 29;52(1):962.
doi: 10.1007/s11033-025-11066-1.

Unraveling ESBL and AmpC resistance in multi-drug resistant Klebsiella pneumoniae: phenotypic and genotypic insights

Mohammed Majeed Ali  1 , Arumugam Suresh  2 , Natarajan Muninathan  1 , Kuppusamy Baskaran  1 , Venugopal Gopikrishnan  3 , Mohammad Z Ahmed  4 , Ali S Alqahtani  4 , M Dhinakaran  5 , Shobana Sampath  6
Affiliations

Unraveling ESBL and AmpC resistance in multi-drug resistant Klebsiella pneumoniae: phenotypic and genotypic insights

Mohammed Majeed Ali et al. Mol Biol Rep. .

Abstract

Background: The rise of Antimicrobial Resistant Klebsiella pneumoniae poses a major public health threat. This study explores the phenotypic and genotypic epidemiology of Multi-Drug Resistant (MDR) K. pneumoniae, focusing on ESBL and AmpC-producing strains, through a global analysis of molecular epidemiology.

Materials and methods: A study was conducted on 200 Klebsiella pneumoniae isolates from various clinical specimens to assess antimicrobial resistance, ESBL, AmpC beta-lactamases, and hypervirulence. Phenotypic methods, including Kirby-Bauer disk diffusion, Combination Disc Test, Disc Approximation, and String test, were used. Molecular analysis via Multiplex PCR for genetic determinants of resistance and virulence factors. The findings were entered into the Microsoft Excel Version 2010. Statistical analysis was carried out using SPSS Version 20. Observed association between ESBL, AmpC resistance and hvK.pneumoniae with clinical specimens by calculating the p-value using the chi-square test (p-value of 0.012885 i.e., p < 0.05 was considered significant).

Results: High-level resistance was observed in K. pneumoniae strains against third-generation cephalosporins, amoxicillin/clavulanate, and piperacillin/tazobactam. Of the isolates, 29.5% exhibited ESBL activity, 25% AmpC beta-lactamase, and 9.5% hypervirulence activity. ESBL-producing isolates had blaSHV 35.7%, blaTEM 31.7%, blaCTX-M2 46.6%, and blaCTX-M1 10.9%. AmpC producers showed blaFOX-M 78.8% and blaCMY/MOX 50%. Virulence gene prevalence included magA (K1) in 56%, K2 serotype in 20%, rmpA in 9.5%, mrkD in 66%, entB in 63%, iutA in 49%, kfu in 17%, and allS in 11%.

Conclusion: The study's findings on antibiotic resistance, phenotypic, and genotypic analysis of K. pneumoniae will establish a foundational dataset in present scenario, which will serve as a reference point for determining susceptibility levels and implementation of targeted therapy in the event of potential MDR strains of K.pneumoniae isolate outbreaks and for further Additional studies in this related area intrest.

Keywords: Antimicrobial resistance; Hypervirulence; K.pneumoniae; Molecular epidemiology.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests. Ethical approval: Not applicable.

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