Antimicrobial Resistance Patterns of Vibrio cholera Strains Isolated From Afghan and Iranian Patients in Iran

The increasing prevalence of multidrug resistant strains of Vibrio cholerae in recent cholera epidemics across the world is a growing global public health challenge. This study was undertaken to identify the patterns of antimicrobial resistance in isolates collected from laboratory-confirmed cases of cholera during an outbreak occurred between August and September 2013 in Sistan and Balouchestan province, southeast of Iran. Forty eight V. cholerae isolates were obtained from clinical samples. All the strains were identified as Inaba serotype. Antibiotic susceptibility of the isolates for sulfamethoxazole-trimethoprim, tetracycline, nalidixic acid, ciprofloxacin, ampicillin, ceftriaxone and erythromycin were determined. The method used for antimicrobial susceptibility testing (AST) was standard disk diffusion technique (Kirby-Bauer method). According to the criteria published by the Clinical and Laboratory Standards Institute (CLSI), the isolates were characterized as susceptible, intermediate, or resistant. A ST revealed high levels of resistance to sulfamethoxazole-trimethoprim (89.6%), tetracycline (60.4%), ampicillin (56.3%), nalidixic acid (43.7%) and erythromycin (22.9%). Intermediate susceptibility levels to erythromycin (68.8%), nalidixic acid (56.3%) and ampicillin (33.3%) were identified. All the samples were susceptible to ciprofloxacin and ceftriaxone. Resistant to erythromycin, sulfamethoxazole-trimethoprim and ampicillin dominated in Afghan patients' samples, while a greater proportion of samples from Iranian patients showed resistance to tetracycline and nalidixic acid. All the differences were statistically significant. Our findings suggested a worrying increase in resistance of V. cholerae strains to commonly used antibiotics. Differences in patterns of resistance between Afghan and Iranian patients' samples were observed, which further emphasize a need for constant observation