Molecular epidemiology of Vibrio cholerae in the U.S. Gulf Coast

Abstract

Enterotoxigenic strains of V. cholerae 0-1, biotype El Tor, isolated from a case of cholera in Texas in 1973, an outbreak of cholera in Louisiana in 1978 and Louisiana sewage samples in 1980 and 1981 were analyzed for their genetic similarities. Chromosomal DNA was isolated from each strain, digested with restriction endonuclease and analyzed by the Southern blot technique. A radioactive probe consisting of Escherichia coli heat-labile enterotoxin DNA detected cholera toxin gene sequences in these strains and demonstrated that the toxin gene sequence, if not the entire chromosomal DNA, is identical in these strains and distinctly different from other strains of V. cholerae isolated throughout the world. In addition, 2 strains of enterotoxigenic V. cholerae non-0-1 isolated from clinical (human) cases, were analyzed and found to possess cholera toxin genes which differed in the DNA sequence from the V. cholerae 0-1 strains. Thus a single strain of enterotoxigenic V. cholerae 0-1 is apparently resident in the USA Gulf Coast. A 2nd reservoir of cholera toxin genes seemingly exists in V. cholerae non-0-1 strains in Louisiana.