Detection of AcrAB efflux pump mediated ciprofloxacin resistance in Escherichia coli and Klebsiella pneumoniae in Nepal.

Background: Antimicrobial resistance (AMR) has emerged as a serious public health threat with a sharply increasing burden globally. Resource limited countries like Nepal are facing difficulties in the fight against AMR. This has been further worsened due to the lack of adequate molecular data. Ciprofloxacin resistance by AcrAB-TolC efflux pump (EP) genes in Gram-negative bacteria becomes a challenging issue due to its potential role in multidrug resistance (MDR). This hospital-based cross-sectional study investigated these genes in ciprofloxacin-resistant Escherichia coli and Klebsiella pneumoniae isolates from patients attending a tertiary care hospital in Kathmandu, Nepal. Different clinical specimens (n = 877) were subjected to bacterial isolation and identification. Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion technique and minimum inhibitory concentration (MIC) by agar dilution. AcrAB-TolC genes were detected by polymerase chain reaction (PCR).

Results: Out of 877 samples, 124 (14.1%) showed bacterial growth, comprising 59 (47.6%) E. coli, 39 (31.4%) K. pneumoniae, and 26 (20.9%) other bacterial species. MDR was observed in 66.1% of E. coli and 89.7% of K. pneumoniae. Ciprofloxacin resistance was seen in 57.6% of E. coli and 71.8% of K. pneumoniae isolates. Majority of E. coli (10) and K. pneumoniae (8) isolates showed MIC of ciprofloxacin as 256 µg/mL and 512 µg/mL, respectively. There was significant association between ciprofloxacin resistance and MDR (p < 0.05). The higher proportion of AcrAB-TolC genes was detected in ciprofloxacin-resistant MDR isolates of E. coli (87.5%) and K. pneumoniae (66.7%) compared to non-MDR isolates.

Conclusions: Clinical isolates of E. coli and K. pneumoniae exhibited alarmingly high MDR rates with substantial resistance to commonly prescribed antibiotics in Nepal. We also observed a notable presence of EP-mediated resistance in these isolates. These findings highlight the urgent need for enhanced AMR surveillance (including resistance marker screening and genomic surveillance) and development of evidence-based antibiotic stewardship programs to address the growing burden of MDR Nepal.