Phenotypic and Genetic Analysis of Antimicrobial Susceptibility in Vibrio cholerae Isolates Collected Between 1970...

This study aimed to evaluate the antimicrobial susceptibility and identify genetic determinants of resistance in Vibrio cholerae strains maintained in the culture collection of the Masgut Aikimbayev National Scientific Center for Especially Dangerous Infections (NSCEDI, Republic of Kazakhstan). The analyzed isolates were previously obtained from various environmental and laboratory sources as part of microbiological and epidemiological surveillance conducted between 1970 and 2024.

Twenty-six V. cholerae isolates representing different serogroups were analyzed using phenotypic and molecular methods. Antimicrobial susceptibility was determined by the Kirby-Bauer disk diffusion test and E-test against 59 antibacterial agents from major pharmacological classes. The presence of resistance genes to β-lactams and glycopeptides was examined using the BacResista GLA Real-Time PCR Detection Kit (DNA-Technology LLC, Moscow, Russia).

All V. cholerae isolates demonstrated high susceptibility to key antibiotics, including doxycycline, ciprofloxacin, tetracycline, cefotaxime, and kanamycin. Sporadic intermediate resistance was observed to nalidixic acid, trimethoprim, and streptomycin. Real-time PCR screening did not detect any β-lactamase or glycopeptide resistance genes among the isolates.

The Vibrio cholerae strains preserved in the NSCEDI collection and isolated during 1970-2024 remain highly susceptible to first-line antibiotics and lack molecular markers of resistance. These findings confirm the continued effectiveness of current antimicrobial regimens for cholera treatment and underscore the importance of ongoing national surveillance of antimicrobial resistance to ensure preparedness and biosafety in potential outbreak situations.