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Sensitivity of Escherichia coli O157 detection in bovine feces assessed by broth enrichment followed by immunomagnetic separation and direct plating methodologies.
J Clin Microbiol. 2006 Mar; 44(3):872-5.JC

Abstract

In order to more precisely predict food safety risks, the fecal presence of food-borne pathogens among animals at slaughter must be correctly determined. Quantification of Escherichia coli O157 is also desirable. In two separate experiments, detection and enumeration of a nalidixic acid-resistant strain of E. coli O157 in bovine feces was assessed by culture on MacConkey agar supplemented with nalidixic acid (MACnal) and compared to overnight broth enrichment followed by immunomagnetic separation (IMS) and to direct plating of dilutions of bovine feces onto sorbitol MacConkey agar containing cefixime and tellurite (SMACct). The sensitivity of detection of E. coli O157 by both direct plating and IMS was highly dependent upon the initial concentration of the target organism in the sample. Sensitivity of detection by IMS was poor below 100 CFU/g but was better, and not affected by initial E. coli O157 numbers, above this concentration. Sensitivity of detection of E. coli O157 in bovine feces at low initial concentrations is very poor for both direct plating and IMS. Direct plating of dilutions of bovine feces on SMACct can be used to determine the magnitude of fecal E. coli excretion among cattle excreting greater than 100 CFU/g. Among positive samples identified by direct plating on SMACct, the direct counts of E. coli O157:H7 were highly correlated with the estimates obtained with the MACnal plates (r = 0.88, P < 0.001). Because the majority of cattle excrete less than 10(2) CFU E. coli O157/g feces, most studies, including those using IMS methods, probably grossly underestimate the prevalence of E. coli O157 in cattle.

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Authors+Show Affiliations

LeJeune JT
Food Animal Health Research Program, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Ave., Wooster, Ohio 44691, USA. lejeune.3@osu.edu
Hancock DD
No affiliation info available
Besser TE
No affiliation info available

MeSH

AnimalsBacteriological TechniquesCattleColony Count, MicrobialCulture MediaEscherichia coli O157FecesFood MicrobiologyImmunomagnetic SeparationMaleSensitivity and Specificity

Pub Type(s)

Comparative Study
Evaluation Study
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

16517869

Citation

LeJeune, Jeffrey T., et al. "Sensitivity of Escherichia Coli O157 Detection in Bovine Feces Assessed By Broth Enrichment Followed By Immunomagnetic Separation and Direct Plating Methodologies." Journal of Clinical Microbiology, vol. 44, no. 3, 2006, pp. 872-5.
LeJeune JT, Hancock DD, Besser TE. Sensitivity of Escherichia coli O157 detection in bovine feces assessed by broth enrichment followed by immunomagnetic separation and direct plating methodologies. J Clin Microbiol. 2006;44(3):872-5.
LeJeune, J. T., Hancock, D. D., & Besser, T. E. (2006). Sensitivity of Escherichia coli O157 detection in bovine feces assessed by broth enrichment followed by immunomagnetic separation and direct plating methodologies. Journal of Clinical Microbiology, 44(3), 872-5.
LeJeune JT, Hancock DD, Besser TE. Sensitivity of Escherichia Coli O157 Detection in Bovine Feces Assessed By Broth Enrichment Followed By Immunomagnetic Separation and Direct Plating Methodologies. J Clin Microbiol. 2006;44(3):872-5. PubMed PMID: 16517869.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Sensitivity of Escherichia coli O157 detection in bovine feces assessed by broth enrichment followed by immunomagnetic separation and direct plating methodologies. AU - LeJeune,Jeffrey T, AU - Hancock,Dale D, AU - Besser,Thomas E, PY - 2006/3/7/pubmed PY - 2006/6/6/medline PY - 2006/3/7/entrez SP - 872 EP - 5 JF - Journal of clinical microbiology JO - J Clin Microbiol VL - 44 IS - 3 N2 - In order to more precisely predict food safety risks, the fecal presence of food-borne pathogens among animals at slaughter must be correctly determined. Quantification of Escherichia coli O157 is also desirable. In two separate experiments, detection and enumeration of a nalidixic acid-resistant strain of E. coli O157 in bovine feces was assessed by culture on MacConkey agar supplemented with nalidixic acid (MACnal) and compared to overnight broth enrichment followed by immunomagnetic separation (IMS) and to direct plating of dilutions of bovine feces onto sorbitol MacConkey agar containing cefixime and tellurite (SMACct). The sensitivity of detection of E. coli O157 by both direct plating and IMS was highly dependent upon the initial concentration of the target organism in the sample. Sensitivity of detection by IMS was poor below 100 CFU/g but was better, and not affected by initial E. coli O157 numbers, above this concentration. Sensitivity of detection of E. coli O157 in bovine feces at low initial concentrations is very poor for both direct plating and IMS. Direct plating of dilutions of bovine feces on SMACct can be used to determine the magnitude of fecal E. coli excretion among cattle excreting greater than 100 CFU/g. Among positive samples identified by direct plating on SMACct, the direct counts of E. coli O157:H7 were highly correlated with the estimates obtained with the MACnal plates (r = 0.88, P < 0.001). Because the majority of cattle excrete less than 10(2) CFU E. coli O157/g feces, most studies, including those using IMS methods, probably grossly underestimate the prevalence of E. coli O157 in cattle. SN - 0095-1137 UR - https://www.unboundmedicine.com/medline/citation/16517869/Sensitivity_of_Escherichia_coli_O157_detection_in_bovine_feces_assessed_by_broth_enrichment_followed_by_immunomagnetic_separation_and_direct_plating_methodologies_ DB - PRIME DP - Unbound Medicine ER -