title: Genotype, serotype, and antibiotic resistance of sorbitol-negative Escherichia coli isolates from feedlot cattle.
abstract: Rectal fecal samples from 80 steers receiving Rumensin, Revalor-S, and Liquamycin alone or in combination for growth promotion and disease prevention were examined for the presence of non-O157:H7 Shiga toxin-producing Escherichia coli. All isolates were identified with the API 20E test, virulence genes were detected with a PCR assay, and antibiotic susceptibilities were determined with the Sensititre system. Of the 153 E. coli isolates recovered 126 (82.3%) were sorbitol negative. Isolates were classified into 14 biochemical E. coli groups; 51.6% were negative for arginine dihydrolase, ornithine decarboxylase, sorbitol, and saccharose reactions but positive for lysine decarboxylase, indole production, and rhamnose reactions. Twenty-one O:H serotypes were detected in the 153 E. coli isolates. The most frequent serotypes were O2:H42 (49.7% of isolates), O49:NM (13.7%), O?:H25 (9.2%), and O10:NM (7.2%). One isolate of E. coli O172:H25 and one of E. coli O157: H39 were found. The stx1 gene was found in the two E. coli O98:H25 isolates. The eaeA and e-hlyA genes were detected in 21, 14, and 10 isolates of serotypes O49:NM, O?:H25, and O10:NM, respectively, and in each isolate of serotype O156:H25 and O172:H25. Four E. coli O132:H18 isolates were multiresistant to ampicillin, chloramphenicol, kanamycin, streptomycin, and sulfisoxazole. Tetracycline resistance due to the tet(B) gene was observed in 74 of the 76 E. coli O2:H42 isolates. Except for one isolate, all tetracycline-resistant isolates were negative for the virulence genes eaeA and e-hlyA or stx1. Pulsed-field gel electrophoresis typing revealed that the tetracycline-resistant serotypes were genetically diverse. Our data illustrate that cattle are a potential source of some atypical antibiotic-resistant E. coli isolates that harbor virulence genes.
authors.affiliation: Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1000, 6947 Highway 7, Agassiz, British Columbia, Canada V0M 1A0. diarram@agr.gc.ca
authors.forename: Moussa S
authors.initials: MS
authors.lastname: Diarra
authors.forename: Karine
authors.initials: K
authors.lastname: Giguère
authors.forename: François
authors.initials: F
authors.lastname: Malouin
authors.forename: Brigitte
authors.initials: B
authors.lastname: Lefebvre
authors.forename: Susan
authors.initials: S
authors.lastname: Bach
authors.forename: Pascal
authors.initials: P
authors.lastname: Delaquis
authors.forename: Mueen
authors.initials: M
authors.lastname: Aslam
authors.forename: Kim A
authors.initials: KA
authors.lastname: Ziebell
authors.forename: Gabriel
authors.initials: G
authors.lastname: Roy
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D015169:Colony Count, Microbial; D024881:Drug Resistance, Bacterial; D005243:Feces / Q000382:microbiology; D005838:Genotype; D008297:Male; D011897:Random Allocation; D012007:Rectum / Q000382:microbiology*; D012703:Serotyping; D022622:Shiga Toxin 1 / Q000096:biosynthesis / Q000235:genetics; D022641:Shiga Toxin 2 / Q000096:biosynthesis / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification* / Q000187:drug effects* / Q000378:metabolism; D013012:Sorbitol / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; D037521:Virulence Factors; D013012:Sorbitol