GENOTYPE AND DRUG RESISTANCE OF CLINICAL AND ENVIRONMENTAL VIBRIO CHOLERAE NON-O1/ NON-O139 IN NORTHEASTERN THAILAND

A total of 124 V. cholerae non-O1/non-O139 isolates were collected in Khon Kaen, Thailand from diarrheal patients, asymptomatic carriers and environmen- tal water. The presence of virulence-associated and regulatory genes including ctxA, tcpA, zot, ace, ompU, stn, hlyA and toxR) were examined using multiplex PCR. The genomic diversity of the various V. cholerae isolates were differentiated using the random amplified polymorphic DNA (RAPD) method. Antimicrobial susceptibility was tested using disk diffusion. All of V. cholerae non-O1/non-O139 isolates carried hlyA and toxR and none carried ctxA and tcpA. The zot, ace and both genes together were found in 1.6%, 4.7% and 4.7% of 64 clinical V. cholerae non-O1 isolates, respectively, while the environmental ones did not. The stn gene was found in 3.1% (2/64) of the clinical and 3.3% (2/60) of the environmental iso- lates. The RAPD patterns were differentiated into 45 types (A to 2S). RAPD type A (32.3%) was the most frequently found in both clinical and environmental V. cholerae non-O1 strains (34.4% and 30.0%, respectively); indicating that there was a clonal relationship between some clinical and environmental isolates whereas almost all of the environmental isolates belonged to different clones. All strains were sensitive to ciprofloxacin and norfloxacin. The environmental isolates (30%) were more resistant than the clinical ones (21.9%). Resistance to sulfamethoxa- zole/trimethoprim and tetracycline among the clinical isolates occurred in 9.4% (6/64) in 2007, during which period the prevalence of V. cholerae O1 increased. We conclude that V. cholerae non-O1/non-O139 from the aquatic environment are potentially pathogenic and this same aquatic environment may be a source of antimicrobial resistance in V. cholerae.