Molecular insights and antibiotic resistance genes characterization in clinical Vibrio cholera isolates from patients in Peshawar, Pakistan

Abstract

Background Vibrio cholerae, the causative agent of cholera, remains a significant public health concern in various regions of the world, including Pakistan. This study aimed to investigate the antibiotic susceptibility profiles and molecular characterization of V. cholerae during a diarrheal outbreak in Peshawar, Pakistan, from July 2023 to July 2025. Methods A total of 90 stool samples were collected, among which 68 (75.5%) isolates were identified as V. cholerae. Antibiotic susceptibility testing was performed to determine resistance and susceptibility patterns. Statistical analysis was conducted to evaluate the association of infection with age and gender demographics. PCR analysis was used to detect the presence of antibiotic resistance genes among the isolates. Results The highest infection rate was observed in males (n = 40, 59%) and in the ≤ 18 years age group (n = 36, 53%). Antibiotic susceptibility testing revealed complete resistance to erythromycin (ERY) and levofloxacin (LVX), with all 13/13 isolates (100%) showing resistance. High resistance was also observed against azithromycin (AZM; 12/13, 92.3%), tetracycline (TET; 11/13, 84.6%), trimethoprim-sulfamethoxazole (SXT; 10/13, 76.9%), ampicillin (AMP; 9/13, 69.2%), and ceftriaxone (CRO; 9/13, 69.2%). However, amikacin (AMK; 8/13, 61.5%) and ciprofloxacin (CIP; 7/13, 53.8%) showed the highest susceptibility. Statistical analysis showed no significant correlation for age demographics (χ² = 0.042, p = 0.979) and gender distribution (χ² = 1.41, df = 1, p = 0.235). PCR analysis revealed a high prevalence of resistance genes, including dfrA1 (n = 12, 92.3%), sul1 (n = 12, 92.3%), sul2 (n = 10, 76.9%), tetA (n = 10, 76.9%), blaTEM (n = 11, 84.6%), blaCTX-M (n = 9, 69.2%), blaOXA (n = 8, 61.5%), blaSHV (n = 6, 38.5%), and mcr-1 (n = 7, 53.8%). The detection of mcr-1 is particularly concerning because of its association with colistin resistance. Conclusion The findings highlight the alarming pattern of multidrug resistance in V. cholerae isolates from Peshawar, emphasizing the necessity for effective surveillance and control strategies to prevent the spread of antibiotic-resistant strains.

Keywords: Vibrio cholerae; blaTEM; Antibiotic susceptibility test; MEM; Multi-drug resistant.