title: Non-O157 Shiga toxin-producing Escherichia coli isolated from diarrhoeic calves in Argentina.
abstract: Faecal samples from 76 diarrhoeic calves belonging to 36 farms located in the Pampas plain, Argentina, were examined for Shiga toxin-producing Escherichia coli (STEC). A total of 15 STEC strains were isolated from 12 (15.8%) calves which came from six different farms. All stx positive strains assayed by PCR were also positives in the Vero cell cytotoxicity test. The majority (60.0%) of the STEC strains carried the stx(1) gene. Twelve (80.0%) of the STEC isolates which belonged to serotypes O5:H- (n = 4), O26:H11 (n = 4), O26:H- (n = 1), O111:H- (n = 2), and O123:H38 (n = 1) were also enterohaemolysin (EHly) positive and carried the gene encoding for intimin (eae). All the stx positive strains were negative for the bfpA gene. Localized adherence to HEp-2 cells were observed in 83.3% of the eae+ STEC strains. STEC belonging to serotype O5:H- showed atypical biochemical properties, including urease production. Urease was also produced by two strains belonging to serotypes O153:H? and non-typeable, respectively. Resistance to three or more antibiotics was observed in 12 (80.0%) of the STEC isolates. Most of the serotypes of STEC recovered in this survey carried virulence traits that are associated with increased human and bovine pathogenicity. The present study shows that highly virulent STEC strains are being shed by diarrhoeic calves from farms located in a high incidence area of human STEC infections.
authors.affiliation: Instituto de Patobiología, Instituto Nacional de Technologia Agropecuaria (INTA), Los Reseros y Las Canbanas, (1686) Hurlingham, Prov. Buenos Aires, Argentina. emercado@cicv.inta.gov.ar
authors.forename: E C
authors.initials: EC
authors.lastname: Mercado
authors.forename: A
authors.initials: A
authors.lastname: Gioffré
authors.forename: S M
authors.initials: SM
authors.lastname: Rodríguez
authors.forename: A
authors.initials: A
authors.lastname: Cataldi
authors.forename: K
authors.initials: K
authors.lastname: Irino
authors.forename: A M
authors.initials: AM
authors.lastname: Elizondo
authors.forename: A L
authors.initials: AL
authors.lastname: Cipolla
authors.forename: M I
authors.initials: MI
authors.lastname: Romano
authors.forename: R
authors.initials: R
authors.lastname: Malena
authors.forename: M A
authors.initials: MA
authors.lastname: Méndez
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001118:Argentina / Q000453:epidemiology; D001422:Bacterial Adhesion; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000209:etiology / Q000382:microbiology; D017931:DNA Primers; D004269:DNA, Bacterial / Q000032:analysis; D003967:Diarrhea / Q000453:epidemiology / Q000662:veterinary*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000662:veterinary; D022603:Shiga Toxins
chemical_list: D000890:Anti-Infective Agents; D017931:DNA Primers; D004269:DNA, Bacterial; D022603:Shiga Toxins