title: Occurrence, virulence genes and antibiotic resistance of Escherichia coli O157 isolated from raw bovine, caprine and ovine milk in Greece.
abstract: The examination of 2005 raw bovine (n = 950), caprine (n = 460) and ovine (n = 595) bulk milk samples collected throughout several regions in Greece for the presence of Escherichia coli serogroup O157 resulted in the isolation of 29 strains (1.4%) of which 21 were isolated from bovine (2.2%), 3 from caprine (0.7%) and 5 from ovine (0.8%) milk. Out of the 29 E. coli O157 isolates, only 12 (41.4%) could be classified as Shiga-toxigenic based on immunoassay and PCR results. All 12 Shiga-toxigenic E. coli serogroup O157 isolates belonged to the E. coli O157:H7 serotype. All except one of the 12 Shiga-toxin positive isolates were stx(2)-positive, five of which were also stx(1)-positive. The remaining isolate was positive only for the stx(1) gene. All stx-positive isolates (whether positive for stx(1), stx(2) or stx(1) and stx(2)) were also PCR-positive for the eae and ehxA genes. The remaining 17 E. coli O157 isolates (58.6%) were negative for the presence of the H7 flagellar gene by PCR, tested negative for Shiga-toxin production both by immunoassay and PCR, and among these, only four and three strains were PCR-positive for the eae and ehxA genes, respectively. All 29 E. coli O157 isolates displayed resistance to a wide range of antimicrobials, with the stx-positive isolates being, on average, resistant to a higher number of antibiotics than those which were stx-negative.
authors.affiliation: Laboratory of Hygiene of Foods of Animal Origin, Faculty of Veterinary Medicine, University of Thessaly, 43100 Karditsa, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Solomakos
authors.forename: Alexandros
authors.initials: A
authors.lastname: Govaris
authors.forename: Apostolos S
authors.initials: AS
authors.lastname: Angelidis
authors.forename: Spyros
authors.initials: S
authors.lastname: Pournaras
authors.forename: Angeliki Rothi
authors.initials: AR
authors.lastname: Burriel
authors.forename: Spyridon K
authors.initials: SK
authors.lastname: Kritas
authors.forename: Demetrios K
authors.initials: DK
authors.lastname: Papageorgiou
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D019453:Escherichia coli O157 / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006041:Goats; D006115:Greece; D006801:Humans; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000382:microbiology*; D015995:Prevalence; D012756:Sheep; D022603:Shiga Toxins / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D022603:Shiga Toxins; D037521:Virulence Factors