Abstract
A total of 31 strains of Vibrio cholerae O1 (10 from outbreak cases and 7 from surface water)
and non-O1 (4 from clinical and 10 from surface water sources) isolated between 1993 and
1997 were examined with respect to presence of cholera enterotoxin (CT) gene by PCR-based
assays, resistance to antibiotics, plasmid profiles and random amplified polymorphic DNA
(RAPD) analysis. All were resistant to 9 or more of the 17 antibiotics tested. Identical
antibiotic resistance patterns of the isolates may indicate that they share a common mode of
developing antibiotic resistance. Furthermore, the multiple antibiotic resistance indexing
showed that all strains tested originated from high risk contamination. Plasmid profile analysis
by agarose gel electrophoresis showed the presence of small plasmids in 12 (7 non-O1 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-O1 serotype) isolates from environmental
waters. The genetic relatedness of the clinical and environmental Vibrio cholerae O1 and non-O1 strains was investigated by RAPD fingerprinting with four primers. The four primers
generated polymorphisms in all 31 strains of Vibrio cholerae tested, producing bands ranging
from <250 to 4500 bp. The RAPD profiles revealed a wide variability and no correlation with
the source of isolation. This study provides evidence that Vibrio cholerae O1 and non-O1 have
significant public health implications.