title: Screening procedure from cattle feces and the prevalence of Escherichia coli O157:H7 in Taiwan dairy cattle.
abstract: A procedure has been established for screening Escherichia coli O157:H7 from bovine feces. It consists of four steps: enrichment, selective culture, phenotyping and genotyping. Modified trypticase soy broth (mTSB) containing 20 microg/mL of novobiocin was used for the enrichment step. The selective culture step was done using sorbitol MacConkey agar containing 0.05 microg/mL of cefixime and 2.5 microg/mL of potassium tellurite. The phenotyping steps include: species confirmation as E. coli, serotyping to O157 and H7, and the detection of verocytotoxin (VT) production. Genotyping was made up of confirmation of the presence of the O157 antigen (rfb), the H7 antigen (ficC), the adherence factor (eaeA), hemolysin (hlyA), and VT production (vt I and vt II) by polymerase chain reaction. mTSB gave better enrichment for E. coli O157 than gram-negative (GN) broth. The detection limit for this screening procedure was 0.85 +/- 0.5 cfu/g. Using the screening procedure described above, E. coli O157 was found in four out of 3062 (0.13%) fresh bovine fecal specimens, and in two out of 78 (2.56%) dairy herds in Taiwan. Three out of the four detected strains were vt II producing E. coli O157:H7, while the other was E. coli O157:H7 which lacked VT-producing ability.
authors.affiliation: Institute of Veterinary Medicine, National Taiwan University, Taipei, ROC.
authors.forename: Y L
authors.initials: YL
authors.lastname: Lin
authors.forename: C C
authors.initials: CC
authors.lastname: Chou
authors.forename: T M
authors.initials: TM
authors.lastname: Pan
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology; D015169:Colony Count, Microbial; D003470:Culture Media; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D005243:Feces / Q000382:microbiology*; D005260:Female; D005784:Gene Amplification; D005838:Genotype; D008403:Mass Screening / Q000662:veterinary; D010641:Phenotype; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012680:Sensitivity and Specificity; D022603:Shiga Toxins / Q000096:biosynthesis; D013624:Taiwan / Q000453:epidemiology
chemical_list: D003470:Culture Media; D022603:Shiga Toxins