Emergence of Vibrio cholerae O1 Biotype El Tor serotype Inaba in north India.

All cases of cholera that have occurred at our center in north India have been due to Vibrio cholerae O1 serotype Ogawa, including the outbreaks in 2002 and 2004. Here we report the emergence of V. cholerae O1 biotype El Tor serotype Inaba for the first time in this region since July 2004. Fifteen Inaba isolates were obtained from 32 patients suffering from cholera-like illness. The patients lived in Chandigarh and the neighboring states of Punjab, Haryana, and Himachal Pradesh. All strains were resistant to nalidixic acid and trimethoprim, and showed moderate sensitivity to amoxycillin. All were sensitive to ciprofloxacin, tetracycline, cefotaxime, amikacin, and gentamicin. All strains were found to be toxigenic when tested with a commercial reverse passive latex agglutination kit. The last reported Inaba isolate dominance in India was observed in Calcutta in 1989. There is a need to closely watch the spread of serotype Inaba, as it may cause outbreaks in other parts of India; molecular studies are warranted to understand the widespread emergence of Inaba in north India.