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Molecular and Phenotypic Characterization of ESBL- and Carbapenemase-Producing Gram-Negative Bacteria in Clinical Isolates from Peshawar, Pakistan
Jawad Ahmad , Hammad Ahmed Abbasi * , Muhammad Atif , Fawad Khan
Institute of Biotechnology and Genetic Engineering, University of Agriculture, Peshawar, Pakistan
Abstract:   (13 Views)
Introduction: The rising prevalence of extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacteria and carbapenem-resistant Enterobacteriaceae (CRE) pose significant threats to public health. Methods: This study investigated the prevalence and antibiotic resistance patterns of ESBL-producing Gram-negative bacteria isolated from various clinical samples in Peshawar, Pakistan. Out of 400 samples, 150 (37.5%) were ESBL-positive, including 50 (33.3%) from urine, 50 (33.3%) from indwelling devices, 25 (16.7%) from pus, and 25 (16.7%) from blood. Escherichia coli was the most prevalent species (57.3%), followed by Klebsiella pneumoniae (34.0%). Antibiotic susceptibility testing revealed that all ESBL-producing isolates (n=150) were resistant to ampicillin, cefoperazone, and ceftazidime, excluding intermediate results as per CLSI 2023 guidelines. PCR assays characterized β-lactamase genes, with bla-CTX-M detected in 95.3% of ESBL-producing isolates, followed by bla-TEM (80.6%) and bla-SHV (70.6%). The Modified Hodge Test showed that 14.7% (22/150) of ESBL isolates were carbapenem-resistant, of which a concerning 86.4% (19/22) carried the blaNDM gene. Results: Statistical analysis revealed a significant association between sample type and ESBL positivity (χ²=16.67, P=0.0008), with the highest prevalence in urine samples. However, no significant difference in carbapenem resistance was found between E. coli and K. pneumoniae (χ²=0.0, P=1.000). The presence of the bla_NDM gene was very strongly associated with carbapenem resistance (χ²=101.42, P<0.0001; Cramer’s V=0.82). Conclusion: The high prevalence of ESBL-producing isolates, predominantly carrying the blaCTX-M gene, and the emergence of blaNDM-mediated carbapenem resistance in Peshawar highlight an urgent need for enhanced surveillance and targeted antimicrobial stewardship to guide effective treatment strategies and public health interventions.
 
Keywords: Antimicrobial resistance, blaCTX-M, blaNDM, Carbapenem resistance, Escherichia coli, ESBL, Klebsiella pneumoniae, Modified Hodge Test, Pakistan, PCR
     
Type of Study: Original article | Subject: Anti-microbial agents, resistance and treatment protocols
Received: 2025/03/17 | Accepted: 2025/09/10
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Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.