title: Hybridization of Escherichia coli producing Shiga-like toxin I, Shiga-like toxin II, and a variant of Shiga-like toxin II with synthetic oligonucleotide probes.
abstract: Synthetic oligonucleotides, constructed from the nucleotide sequences of genes coding for the A subunit of Shiga-like toxin (SLT) I and the B subunit of SLT-II, were used as probes at different degrees of stringency to identify Escherichia coli producing different types of SLTs. At 45 degrees C, the A-I oligonucleotide probe hybridized with E. coli producing SLT-I, SLT-II, and variant of SLT-II (SLT-IIv). At 53 degrees C, only SLT-I-producing E. coli hybridized with this probe. At 45 degrees C, the B-II oligonucleotide probe hybridized with SLT-II- and SLT-IIv-producing E. coli. At 53 degrees C, this probe hybridized with only SLT-II-producing E. coli. The A-I and B-II oligonucleotide probes were subsequently tested for hybridization with 73 SLT-producing E. coli and 49 non-SLT-producing E. coli isolated in Asia and Canada. At 45 degrees C, the A-I oligomer had a sensitivity of 97% and a specificity of 100% in identifying SLT-producing E. coli. At 53 degrees C, the A-I oligonucleotide probe had a sensitivity of 92% and a specificity of 91% in identifying E. coli containing genes encoding SLT-I. At 45 degrees C, the B-II oligonucleotide had a 100% sensitivity and 97% specificity in identifying E. coli that hybridized with the SLT-II probe. Of 17 E. coli that hybridized only with the SLT-II probe, 10 did not hybridize with the B-II oligonucleotide at 53 degrees C. All 10 isolates were cytotoxic to Vero cells but not to HeLa cells, confirming that the B-II oligonucleotide probe used at 53 degrees C will differentiate isolates producing SLT-II and SLT-IIv.
authors.affiliation: Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: J E
authors.initials: JE
authors.lastname: Brown
authors.forename: O
authors.initials: O
authors.lastname: Sethabutr
authors.forename: M P
authors.initials: MP
authors.lastname: Jackson
authors.forename: S
authors.initials: S
authors.lastname: Lolekha
authors.forename: P
authors.initials: P
authors.lastname: Echeverria
mesh_terms: D000328:Adult; D000818:Animals; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics / Q000633:toxicity; D002522:Chlorocebus aethiops; D003603:Cytotoxins / Q000633:toxicity; D004926:Escherichia coli / Q000235:genetics*; D005516:Food Microbiology; D014644:Genetic Variation; D006367:HeLa Cells; D006801:Humans; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes / Q000138:chemical synthesis; D022622:Shiga Toxin 1; D014709:Vero Cells
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D015345:Oligonucleotide Probes; D022622:Shiga Toxin 1