Quinolone susceptibility of Vibrio cholerae O1 & O139 isolates from Vellore.
OBJECTIVE
Vellore is an endemic area for cholera. The relative prevalence of clinical cases of Vibrio cholerae O1 and O139 has been fluctuating. Few studies have examined the susceptibility of local isolates to quinolones. The objective of the present study was to look at quinolone susceptibility and determine MIC of ciprofloxacin to representative clinical isolates of V. cholerae O1 and O139 in Vellore, obtained between 1997 and 1999.


METHODS
Antimicrobial susceptibility testing of V. cholerae strains was performed by disc diffusion technique and MIC determination by E test.


RESULTS
Five of 30 O1 and all the O139 serogroup isolates were susceptible to nalidixic acid. All isolates of both serogroups were sensitive to norfloxacin. All isolates of both serogroups gave MIC results in the susceptible range to ciprofloxacin; the MICs being lower for V. cholerae O139 (MIC50 = 0.004 microgram/ml and MIC90 = 0.047 microgram/ml) than for O1 serogroup (MIC50 = 0.38 microgram/ml and MIC90 = 0.5 microgram/ml).


CONCLUSIONS
V. cholerae O1 and O139 show differences in quinolone susceptibility, the reason for this is not clear. This could be because of longer exposure of the O1 serogroup to quinolone antimicrobials as compared to the O139 serogroup.
Jesudason
Mary V
MV
Department of Clinical Microbiology, Christian Medical College & Hospital, Vellore, India.
Balaji
V
V
Thomson
C J
CJ
D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D006801:Humans; D007194:India; D008826:Microbial Sensitivity Tests; D009268:Nalidixic Acid / Q000494:pharmacology; D009643:Norfloxacin / Q000494:pharmacology; D041241:Vibrio cholerae O1 / Q000187:drug effects* / Q000302:isolation & purification; D041242:Vibrio cholerae O139 / Q000187:drug effects* / Q000302:isolation & purification
D000890:Anti-Infective Agents; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D009643:Norfloxacin