Enzyme-linked synthetic oligonucleotide probes: non-radioactive detection of enterotoxigenic Escherichia coli in faecal specimens. Nucleic Acids Res

Synthetic oligonucleotides, complementary to unique sequences in the heat stable enterotoxin gene of Escherichia col i specific for humans, were prepared with a 30-atom spacer arm and a 3 ' terminal sulfhydryl group which was coupled to bromoacetyl-derivatized alkaline phosphatase. The resulting direct enzyme-linked oligonucleotide probes, containing one enzyme molecule per oligonucleotide, successfully diagnosed enterotoxigenic Escherichia col i in c l in ical specimens by using a modified colony hybridization method and a colorimetric assay. The procedure is rapid, simple and rel iable with a sensi t iv i ty equivalent to that using 5'-terminally labelled [3 2P]-ol igo-nucleotide probes. The results indicate that the enzyme-labelled oligonucleotide probes should be applicable to the routine diagnosis of enterotoxigenic Escherichia col i and possess the potential for the detection of other microbial pathogens