Detection of heat-stable enterotoxin genes among Australian Vibrio cholerae O1 strains.

DNA probes derived from the heat-stable enterotoxin gene of Vibrio cholerae non-O1 (stn), and the cholera toxin gene (ctx), were used to screen 199 strains of V. cholerae O1, which were isolated within Australia 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 before and after heating at 100 degrees C for 5 min. Genetic relationships among the 13 stn+ strains were studied by a comparison of the rRNA-RFLPs (ribotyping) and by Southern blot analysis with a stn gene probe. The results indicate that there is a clonal relationship among the Australian stn+ strains and that there is an environmental reservoir of stn genes among Australian V. cholerae O1 isolates.