Molecular and Phenotypic Characterization of ESBL- and Carbapenemase-Producing Gram-Negative Bacteria in Clinical Isolates from Peshawar, Pakistan

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 ۴۰۰ samples, ۱۵۰ (۳۷.۵%) were ESBL-positive, including ۵۰ (۳۳.۳%) from urine, ۵۰ (۳۳.۳%) from indwelling devices, ۲۵ (۱۶.۷%) from pus, and ۲۵ (۱۶.۷%) from blood. Escherichia coli was the most prevalent species (۵۷.۳%), followed by Klebsiella pneumoniae (۳۴.۰%). Antibiotic susceptibility testing revealed that all ESBL-producing isolates (n=۱۵۰) were resistant to ampicillin, cefoperazone, and ceftazidime, excluding intermediate results as per CLSI ۲۰۲۳ guidelines. PCR assays characterized β-lactamase genes, with bla-CTX-M detected in ۹۵.۳% of ESBL-producing isolates, followed by bla-TEM (۸۰.۶%) and bla-SHV (۷۰.۶%). The Modified Hodge Test showed that ۱۴.۷% (۲۲/۱۵۰) of ESBL isolates were carbapenem-resistant, of which a concerning ۸۶.۴% (۱۹/۲۲) carried the blaNDM gene. Results: Statistical analysis revealed a significant association between sample type and ESBL positivity (χ²=۱۶.۶۷, P=۰.۰۰۰۸), with the highest prevalence in urine samples. However, no significant difference in carbapenem resistance was found between E. coli and K. pneumoniae (χ²=۰.۰, P=۱.۰۰۰). The presence of the bla_NDM gene was very strongly associated with carbapenem resistance (χ²=۱۰۱.۴۲, P<۰.۰۰۰۱; Cramer’s V=۰.۸۲). 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.

کلیدواژه ها:

Antimicrobial resistance ، blaCTX-M ، blaNDM ، Carbapenem resistance ، Escherichia coli ، ESBL ، Klebsiella pneumoniae ، Modified Hodge Test ، Pakistan ، PCR