title: Use of nonradioactive DNA hybridization for identification of enterotoxigenic Escherichia coli harboring genes for colonization factor antigen I, coli surface antigen 4, or putative colonization factor O166.
abstract: We developed an accurate nonradioactive colony hybridization assay (NCHA) using a digoxigenin-labeled polynucleotide probe and an antidigoxigenin alkaline phosphatase conjugate for the identification of enterotoxigenic Escherichia coli (ETEC) harboring genes for colonization factor antigen I (CFA/I), coli surface antigen 4 (CS4), or putative colonization factor O166 (PCFO166). In this 2-day assay, visual registration of color intensity could be used to distinguish between CFA/I-positive strains and strains with the genetic potential to express CS4 or PCFO166. A rapid NCHA was developed by which the results could be read visually 7 h and 45 min after inoculation of the bacteria. In the rapid NCHA, densitometry verified the visual discrimination between four groups of E. coli; ETEC with the CFA/I gene, ETEC with the CS4 gene, ETEC with the PCFO166 gene, and E. coli strains that lack such genes. As a confirmatory test, plasmids from ETEC with the CFA/I, CS4, or PCFO166 gene were differentiated by their characteristic restriction fragment patterns in nonradioactive Southern blot hybridization.
authors.affiliation: Centre for International Health, University of Bergen, Haukeland Hospital, Norway.
authors.forename: H
authors.initials: H
authors.lastname: Sommerfelt
authors.forename: H M
authors.initials: HM
authors.lastname: Grewal
authors.forename: W
authors.initials: W
authors.lastname: Gaastra
authors.forename: A M
authors.initials: AM
authors.lastname: Svennerholm
authors.forename: M K
authors.initials: MK
authors.lastname: Bhan
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D000954:Antigens, Surface / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics* / Q000302:isolation & purification; D003720:Densitometry; D004768:Enterotoxins; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D036781:Fimbriae Proteins; D005798:Genes, Bacterial / Q000235:genetics*; D009693:Nucleic Acid Hybridization
chemical_list: D000942:Antigens, Bacterial; D000954:Antigens, Surface; D004269:DNA, Bacterial; D004768:Enterotoxins; C022924:colonization factor antigens; D036781:Fimbriae Proteins