Molecular characterization of Vibrio cholerae O1 and non-O1 from human andenvironmental sources in Malaysia

A total of 31 strains of Vibrio cholerae O1 (10 from outbreak cases and 7 f rom surface water) and non-Ol (4 from clinical and 10 from surface water so urces) isolated between 1993 and 1997 were examined with respect to presenc e of cholera enterotoxin (CT) gene by PCR-based assays, resistance to antib iotics, plasmid profiles and random amplified polymorphic DNA (RAPD) analys is. All were resistant to 9 or more of the 17 antibiotics tested. Identical antibiotic resistance patterns of the isolates may indicate that they shar e a common mode of developing antibiotic resistance. Furthermore, the multi ple antibiotic resistance indexing showed that all strains tested originate d from high risk contamination. Plasmid profile analysis by agarose gel ele ctrophoresis showed the presence of small plasmids in 12 (7 non-Ol and 5 O1 serotypes) with sizes ranging 1.3-4.6 MDa. The CT gene was detected in all clinical isolates but was present in only 14 (6 O1 serotype and 8 non-Ol s erotype) isolates from environmental waters. The genetic relatedness of the clinical and environmental Vibrio cholerae O1 and non-O1 strains was inves tigated by RAPD fingerprinting with four primers. The four primers generate d polymorphisms in all 31 strains of Vibrio cholerae tested, producing band s ranging from < 250 to 4500 bp. The RAPD profiles revealed a wide variabil ity and no correlation with the source of isolation. This study provides ev idence that Vibrio cholerae O1 and non-Ol have significant public health im plications.