High prevalence of multidrug-resistant strains of Vibrio cholerae, in a cholera outbreak in Tehran-Iran, during June-September 2008.

Following the occurrence of suspected cases of Vibrio cholerae in Karaj in 2008, this study was conducted in order to determine whether or not the cases were infected with cholera and, if so, to describe the prevalence of serotypes, route of transmission and the antimicrobial resistance profile. In this cross-sectional study, 6505 rectal swabs were collected from patients with acute gastroenteritis. Serotypes and biotypes of the isolates were determined by standard procedures. The antimicrobial susceptibility of 45 Inaba and 30 non-agglutinating (NAG) strains was determined. From 6505 specimens, 110 (1.69%) were defined as V. cholerae, including 70 (63.3%) V. cholerae O1 serotype Inaba biotype El Tor and 40 (36.4%) NAG Vibrios. The case fatality rate was 0.9%. Inaba strains were 100% resistant to nalidixic acid and amoxicillin, 95.7% resistant to trimethoprim-sulfamethoxazole, 91.3% resistant to furazolidone while the highest frequency of resistance in NAG Vibrios was 77.4% to erythromycin. The lowest resistance rate belonged to ciprofloxacin to which just one NAG strain was resistant. Results suggests an increase in resistance of V. cholerae to several antibiotics. Ciprofloxacin can still be used as first-line treatment of cholera in this region.