Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens, and beef cattle are recognized as the principal reservoir. The aims of this study were (1) to identify the most sensitive combination of selective enrichment broths and agars for STEC isolation in artificially inoculated ground b...

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Autores principales: Brusa, Victoria, Piñeyro Piñeiro, Pablo Enrique, Galli, Lucía, Linares, Luciano Héctor, Ortega, Emanuel Eneas, Padola, Nora Lía, Leotta, Gerardo Aníbal
Formato: Articulo
Lenguaje:Inglés
Publicado: 2016
Materias:
Ciencias Veterinarias
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/154159
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-154159
record_format dspace
spelling I19-R120-10915-1541592023-06-08T20:09:05Z http://sedici.unlp.edu.ar/handle/10915/154159 issn:1556-7125 Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars Brusa, Victoria Piñeyro Piñeiro, Pablo Enrique Galli, Lucía Linares, Luciano Héctor Ortega, Emanuel Eneas Padola, Nora Lía Leotta, Gerardo Aníbal 2016 2023-06-08T18:58:22Z en Ciencias Veterinarias Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens, and beef cattle are recognized as the principal reservoir. The aims of this study were (1) to identify the most sensitive combination of selective enrichment broths and agars for STEC isolation in artificially inoculated ground beef samples, and (2) to evaluate the most efficient combination(s) of methods for naturally contaminated ground beef samples. A total of 192 ground beef samples were artificially inoculated with STEC and non-stx bacterial strains. A combination of four enrichment broths and three agars were evaluated for sensitivity, specificity, and positive predictive value for STEC isolation from experimentally inoculated samples. Enrichments with either modified tryptic soy broth (mTSB) containing 8mg/L novobiocin (mTSB-8) or modified Escherichia coli (mEC) broth followed by isolation in MacConkey agar were the most sensitive combinations for STEC isolation of artificially inoculated samples. Independently, both enrichments media followed by isolation in MacConkey were used to evaluate ground beef samples from 43 retail stores, yielding 65.1% and 58.1% stx-positive samples by RT-PCR, respectively. No difference was observed in the isolate proportions between these two methods (8/25 [32%] and 8/28 [28.6%]). Identical serotypes and stx genotypes were observed in STEC strains isolated from the same samples by either method. In this study, no single enrichment protocol was sufficient to detect all STEC in artificially inoculated samples and had considerable variation in detection ability with naturally contaminated samples. Moreover, none of the single or combinations of multiple isolation agars used were capable of identifying all STEC serogroups in either artificially inoculated or naturally occurring STEC-contaminated ground beef. Therefore, it may be prudent to conclude that there is no single method or combination of isolation methods capable of identifying all STEC serogroups. Instituto de Genética Veterinaria Comisión de Investigaciones Científicas de la provincia de Buenos Aires Articulo Articulo http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International (CC BY 4.0) application/pdf
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Veterinarias
spellingShingle Ciencias Veterinarias
Brusa, Victoria
Piñeyro Piñeiro, Pablo Enrique
Galli, Lucía
Linares, Luciano Héctor
Ortega, Emanuel Eneas
Padola, Nora Lía
Leotta, Gerardo Aníbal
Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars
topic_facet Ciencias Veterinarias
description Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens, and beef cattle are recognized as the principal reservoir. The aims of this study were (1) to identify the most sensitive combination of selective enrichment broths and agars for STEC isolation in artificially inoculated ground beef samples, and (2) to evaluate the most efficient combination(s) of methods for naturally contaminated ground beef samples. A total of 192 ground beef samples were artificially inoculated with STEC and non-stx bacterial strains. A combination of four enrichment broths and three agars were evaluated for sensitivity, specificity, and positive predictive value for STEC isolation from experimentally inoculated samples. Enrichments with either modified tryptic soy broth (mTSB) containing 8mg/L novobiocin (mTSB-8) or modified Escherichia coli (mEC) broth followed by isolation in MacConkey agar were the most sensitive combinations for STEC isolation of artificially inoculated samples. Independently, both enrichments media followed by isolation in MacConkey were used to evaluate ground beef samples from 43 retail stores, yielding 65.1% and 58.1% stx-positive samples by RT-PCR, respectively. No difference was observed in the isolate proportions between these two methods (8/25 [32%] and 8/28 [28.6%]). Identical serotypes and stx genotypes were observed in STEC strains isolated from the same samples by either method. In this study, no single enrichment protocol was sufficient to detect all STEC in artificially inoculated samples and had considerable variation in detection ability with naturally contaminated samples. Moreover, none of the single or combinations of multiple isolation agars used were capable of identifying all STEC serogroups in either artificially inoculated or naturally occurring STEC-contaminated ground beef. Therefore, it may be prudent to conclude that there is no single method or combination of isolation methods capable of identifying all STEC serogroups.
format Articulo
Articulo
author Brusa, Victoria
Piñeyro Piñeiro, Pablo Enrique
Galli, Lucía
Linares, Luciano Héctor
Ortega, Emanuel Eneas
Padola, Nora Lía
Leotta, Gerardo Aníbal
author_facet Brusa, Victoria
Piñeyro Piñeiro, Pablo Enrique
Galli, Lucía
Linares, Luciano Héctor
Ortega, Emanuel Eneas
Padola, Nora Lía
Leotta, Gerardo Aníbal
author_sort Brusa, Victoria
title Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars
title_short Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars
title_full Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars
title_fullStr Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars
title_full_unstemmed Isolation of Shiga Toxin-Producing Escherichia coli from Ground Beef Using Multiple Combinations of Enrichment Broths and Selective Agars
title_sort isolation of shiga toxin-producing escherichia coli from ground beef using multiple combinations of enrichment broths and selective agars
publishDate 2016
url http://sedici.unlp.edu.ar/handle/10915/154159
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