Resistance of Vibrio cholerae 01 to nalidixic acid

Until 1987 all isolates of V. cholerae 01 at a tertiary care hospital in south India were susceptible to drugs commonly used to treat gastroenteritis including cholera. Since July 1987 strains resistant to co-trimoxazole have been encountered and since October 1995 strains resistant to nalidixic acid are being isolated. In this study the latter strains were examined by determining minimum inhibitory concentration levels of nalidixic acid as well as norfloxacin, the fluoroquinolone extensively used to treat diarrhoea. No cross resistance to norfloxacin was found in any of the nalidixic acid resistant V. cholerae 01 strains.