Antimicrobial Resistance Patterns of Isolated Vibrio cholerae Strains

Cholera is a potentially life-threatening acute diarrheal disease caused by the toxigenic bacteria, Vibrio cholerae. Antibiotics should be selected using local antibiotic susceptibility testing patterns. This study was performed to identify the patterns of antimicrobial resistance in isolates collected from laboratory-confirmed cases of cholera during three years, from 2011 to 2013. All isolates at the Health Reference Laboratory were tested by the Minimum Inhibitory Concentration (MIC) Test using Liofilchem against ciprofloxacin, nalidixic acid, cefixime, ampicillin, tetracycline, trimethoprim-sulfamethoxazole, and erythromycin. The following organisms were used as quality control strains for MIC E-testing; Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 29213), and Pseudomonas aeruginosa (ATCC 27853). Results of susceptibility testing showed complete sensitivity to ciprofloxacin, cefixime and amplicillin for both isolated Inaba and Ogawa serotypes except all isolated Inaba serotypes from year 2011, which were resistant to cefixime. These resistant Inaba serotypes were not isolated in the next year. Inaba serotypes showed an increased resistance rate of up to 100% to nalidixic acid, tetracycline and trimethoprim-sulfamethaxazone, while Ogawa serotypes were 100% sensitive at the end of year 2013. The susceptibility pattern of erytromycine was similar in these two types. Sensitivity to erythromycin was decreased in both Inaba and Ogawa serotypes. The analyzed results indicate that tetracycline should not be considered as a first line antibiotic therapy for patients infected with Ogawa serotypes. Also, national guidelines for confirmation of cholera should be improved by responsible authorities to cover new resistance during outbreaks.