Study of the identification of enterotoxigenic Escherichia coli by LT-DNA gene hybridization

Reference strains of enterotoxigenic Escherichia coli (ETEC), non-ETEC, and other enteropathogenic bacteria were used to prove the reliability of LT-DNA gene hybridization. In the test, LT-DNA gene hybridization was compared with plate immunohemolytic test (PIHT) in identifying LT-ETEC. The results obtained by both methods showed no significant differences. 791 strains of E. coli isolated from 1,875 children with acute diarrhea in Taiyuan Children's Hospital were examined for LT-ETEC by LT-DNA gene hybridization and PIHT. 289 strains examined by LT-DNA gene hybridization were LT positive, while 205 strains examined by PIHT were LT positive. Three different assays were done: colony hybridization, PIHT and fecal direct blot hybridization on each of 74 fecal specimens from children with acute diarrhea. It was found that identification of LT-ETEC using fecal direct blot hybridization is a simple, sensitive and more practical method.