Plasmid association and nucleotide sequence relationships of two genes encoding heat-stable enterotoxin production in Escherichia coli H-10407

Plasmid DNA from enterotoxigenic Escherichia coli strains H-10407 and H-10407-P was examined for nucleotide sequence homology to two E. coli genes encoding infant mouse-active heat-stable enterotoxins (ST). A 62-megadalton plasmid of strain H-10407 contained sequences homologous to the gene encoding a toxin designated STIb, previously isolated from a human isolate of E. coli. A 42-megadalton plasmid of strains H-10407 and H-10407-P contained sequences homologous to the gene encoding a toxin designated STIa, previously isolated from bovine and porcine isolates of E. coli.