Antibiotic Sensitivity of Vibrio cholerae Non-O1/Non-O139 Serogroups Isolated from Aquatic Ecosystems

Introduction: The wide spread of V. cholerae non-O1/non-O139 strains resistant to antibacterial drugs and the variability of antibiotic resistance spectrum are of interest and require regional monitoring studies. Our objective was to accumulate basic information on the state of antibiotic sensitivity/resistance of V. cholerae non-O1/non-O139 strains isolated from water bodies in the city of Rostov-on-Don. Materials and methods: Water samples were taken at stationary sites of open reservoirs from May through September 2016–2018. We established sensitivity/resistance of V. cholerae non-O1/non-O139 strains to antibiotics recommended for emergency prevention and treatment of cholera by their serial dilution in Mueller-Hinton agar. Results: We found that representatives of O16 and O76 serogroups prevailed among 361 isolated V. cholerae non-O1/non-O139 strains during the study period. Monoresistant phenotypes were represented by furazolidone-resistant strains. Conclusions: We established a statistically significant increase in the percentage of strains resistant to nalidixic acid (from 4.0% to 13.3%) and chloramphenicol (from 0.5% to 4.4%) in 2016–2018. Resistance to those two antimicrobial drugs was observed in more than one third of the strains. The most common phenotypes were co-trimoxazole/furazolidone and furazolidone/ampicillin. In 2016, the percentage of such phenotypes was 21.4% and 14.8%, in 2017 – 20.0% and 10.6%, and in 2018 – 20.0% and 15.5%, respectively. When analyzing the microorganisms isolated in 2016–2018 and sensitive to three or more antibiotics, we established significant differences indicating the growth of multidrug-resistant microorganisms belonging to V. cholerae non-O1/non-O139 serogroups.