DETECTION OF HEAT-STABLE ENTEROTOXIN GENES AMONG AUSTRALIAN VIBRIO-CHOLERAE O1 STRAINS

DNA probes derived from the heat-stable enterotoxin gene of Vibrio cho lerae non-O1 (stn), and the cholera toxin gene (cbc), were used to scr een 199 strains of V. cholerae O1, which were isolated within Australi a from 1977-1986. 13 environmental strains isolated from the riverine environment in Southeast Queensland in 1980 and 1981, hybridized with the stn and ctx DNA probes. The concentrated supernatant of 6 of these strains elicited fluid accumulation in the infant mouse assay both be fore and after heating at 100 degrees C for 5 min. Genetic relationshi ps among the 13 stn(+) strains were studied by a comparison of the rRN A-RFLPs (ribotyping) and by Southern blot analysis with a stn gene pro be. The results indicate that there is a clonal relationship among the Australian stn(+) strains and that there is an environmental reservoi r of stn genes among Australian V. cholerae O1 isolates.