Antibiotic resistance and β-lactam resistant genes among bacterial isolates from clinical, river water and poultry samples from Kathmandu, Nepal

  

 JAC Antimicrob Resist https://doi.org/10.1093/jacamr/dlaf186 JAC-Antimicrobial Resistance

 

Antibiotic resistance and β-lactam resistant genes among bacterial isolates from clinical, river water and poultry samples from Kathmandu, Nepal

 

Upendra Thapa Shrestha¹, Manash Shrestha², Nabaraj Shrestha³, Komal Raj Rijal¹ and Megha Raj Banjara^1*

 

¹Central Department of Microbiology, Institute of Science and Technology, Tribhuvan University, Kirtipur, Kathmandu, Nepal;

²Asia Pacific Malaria Elimination Network (APMEN), Singapore;

³Central Veterinary Laboratory (CVL), Tripureshwor, Kathmandu, Nepal

 

*Corresponding author. E-mail: megha.banjara@cdmi.tu.edu.np

 

Received 17 August 2025; accepted 25 September 2025

 

Objective: To assess the antibiotic resistance and beta-lactam resistance genes among bacterial isolates from clinical, river water and poultry samples.

Methods: Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were isolated from clinical, poultry and river water samples collected during 2020–22. They were subjected to antimicrobial susceptibility tests following the CLSI guidelines. The bacteria were screened for β-lactam resistance genes blaTEM, mcr-1, mecA and blaNDM-1.

Results: Among 2835 clinical samples, E. coli was the most frequently isolated bacterium (10.3%, 292), followed by S. aureus (6.0%, 169) and P. aeruginosa (4.0%, 143). Of the E. coli isolates, 64.4% exhibited multidrug resistance (MDR) and 43.8% were extended-spectrum β-lactamase (ESBL) producers, with 44.5% and 16.4% harbouring the blaTEM and mcr-1 genes, respectively. Among S. aureus isolates, 80.9% of methicillin-resistant strains (MRSA) carried the mecA gene, while 30.1% of metallo-β-lactamase (MBL)-producing P. aeruginosa were positive for the blaNDM-1 gene. In poultry samples, 30.4% of E. coli isolates harboured the blaTEM gene among 128 ESBL producers, and the prevalence of colistin-resistant isolates carrying mcr-1 was higher than in clinical samples. In contrast, the occurrence of ESBL-producing E. coli and MRSA, along with their associated resistance genes, was lower in water samples.

Conclusions: This study demonstrated widespread multidrug resistance (MDR) and ESBL production among clinical, poultry and river water bacterial isolates in the Kathmandu valley. Colistin-resistant E. coli carrying the mcr-1 gene, methicillin-resistant S. aureus (MRSA) with mecA and metallo-β-lactamase (MBL)-producing P. aeruginosa harboring blaNDM-1 were detected across sources. These findings emphasize an urgent One Health approach to curb the growing threat of antimicrobial resistance in the region.

Citation: Thapa Shrestha U, Shrestha M, Shrestha N, Rijal KR, Banjara MR. Antibiotic resistance and β-lactam resistant genes among bacterial isolates from clinical, river water and poultry samples from Kathmandu, Nepal. JAC Antimicrob Resist. 2025 Oct 17;7(5):dlaf186. doi: 10.1093/jacamr/dlaf186. PMID: 41113068; PMCID: PMC12531798.

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