Competition during enrichment of pathogenic<i>Escherichia coli</i>may result in culture bias

Conrad, Cheyenne C; Stanford, Kim; McAllister, Tim A.; Thomas, James E.; Reuter, Tim

doi:10.1139/facets-2016-0007

Cited by 16 publications

(12 citation statements)

References 28 publications

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“…In fact, VTEC was more likely to be isolated from positive samples using the direct method. The elimination of enrichment reduces the turnaround time from sample to isolate by at least 6–24 h and may help prevent the enrichment culture bias observed during the isolation of VTEC, which is in agreement with other studies involving the isolation of pathogenic E. coli ( Conrad et al, 2016 ), Listeria monocytogenes and Salmonella spp ( Gorski, 2012 ).…”

Section: Discussionsupporting

confidence: 87%

Multi-Year Persistence of Verotoxigenic Escherichia coli (VTEC) in a Closed Canadian Beef Herd: A Cohort Study

Wang

Jokinen²,

Laing

et al. 2018

Front. Microbiol.

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In this study, fecal samples were collected from a closed beef herd in Alberta, Canada from 2012 to 2015. To limit serotype bias, which was observed in enrichment broth cultures, Verotoxigenic Escherichia coli (VTEC) were isolated directly from samples using a hydrophobic grid-membrane filter verotoxin immunoblot assay. Overall VTEC isolation rates were similar for three different cohorts of yearling heifers on both an annual (68.5 to 71.8%) and seasonal basis (67.3 to 76.0%). Across all three cohorts, O139:H19 (37.1% of VTEC-positive samples), O22:H8 (15.8%) and O?(O108):H8 (15.4%) were among the most prevalent serotypes. However, isolation rates for serotypes O139:H19, O130:H38, O6:H34, O91:H21, and O113:H21 differed significantly between cohort-years, as did isolation rates for some serotypes within a single heifer cohort. There was a high level of VTEC serotype diversity with an average of 4.3 serotypes isolated per heifer and 65.8% of the heifers classified as “persistent shedders” of VTEC based on the criteria of >50% of samples positive and ≥4 consecutive samples positive. Only 26.8% (90/336) of the VTEC isolates from yearling heifers belonged to the human disease-associated seropathotypes A (O157:H7), B (O26:H11, O111:NM), and C (O22:H8, O91:H21, O113:H21, O137:H41, O2:H6). Conversely, seropathotypes B (O26:NM, O111:NM) and C (O91:H21, O2:H29) strains were dominant (76.0%, 19/25) among VTEC isolates from month-old calves from this herd. Among VTEC from heifers, carriage rates of vt1, vt2, vt1+vt2, eae, and hlyA were 10.7, 20.8, 68.5, 3.9, and 88.7%, respectively. The adhesin gene saa was present in 82.7% of heifer strains but absent from all of 13 eae+ve strains (from serotypes/intimin types O157:H7/γ1, O26:H11/β1, O111:NM/θ, O84:H2/ζ, and O182:H25/ζ). Phylogenetic relationships inferred from wgMLST and pan genome-derived core SNP analysis showed that strains clustered by phylotype and serotype. Further, VTEC strains of the same serotype usually shared the same suite of antibiotic resistance and virulence genes, suggesting the circulation of dominant clones within this distinct herd. This study provides insight into the diverse and dynamic nature of VTEC populations within groups of cattle and points to a broad spectrum of human health risks associated with these E. coli strains.

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Section: Discussionsupporting

confidence: 87%

Multi-Year Persistence of Verotoxigenic Escherichia coli (VTEC) in a Closed Canadian Beef Herd: A Cohort Study

Wang

Jokinen²,

Laing

et al. 2018

Front. Microbiol.

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“…Owing to the limited sample availability, a multiplex PCR targeting all E. coli O serogroups simultaneously, rather than quantitative PCR (qPCR) assays of each individual O serogroup, was used to determine the presence or absence of each O serogroup in rumen and fecal samples. Although some E. coli O serogroups have been reported to prevail and/or outcompete opponent strains under certain conditions ( 27 ), overall, the total E. coli population was reduced 10-fold when Tasco was included in the diet ( Table 6 ). This suggests that this additive causes a broad-spectrum inhibition of E. coli within the ruminant digestive tract.…”

Section: Discussionmentioning

confidence: 99%

Air-Dried Brown Seaweed, Ascophyllum nodosum , Alters the Rumen Microbiome in a Manner That Changes Rumen Fermentation Profiles and Lowers the Prevalence of Foodborne Pathogens

Zhou

Hünerberg

Chen

et al. 2018

mSphere

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Maintaining product safety and reducing the carbon footprint of production are two sustainability goals of the livestock industry. The objective of this study was to study the impact of Tasco, a product derived from the brown macroalga Ascophyllum nodosum, on the rumen microbiome and its function. The inclusion of Tasco altered both rumen and fecal microbiota levels without affecting rumen fermentation. Tasco reduced fecal Escherichia coli populations and specifically reduced the prevalence of Shiga toxin-producing E. coli O45, O103, O111, and O121 in feces. The findings of this study highlight the application of Tasco as a potential feed additive to reduce pathogen shedding in rams without interfering with ruminal metabolism.

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“…In our experiments, a volume of up to 2 L of drain water could pass before the filtration rate was slowed down (results not shown). In addition, the microbial community in the water may compete with the target pathogen during enrichment (Gorski, 2012; Conrad et al ., 2016).…”

Section: Discussionmentioning

confidence: 99%

Detection of Ralstonia pseudosolanacearum in drain water based on concentration, enrichment and the use of a duplex TaqMan PCR test

et al. 2020

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The Ralstonia solanacearum species complex (RSSC) can cause bacterial wilt in a wide variety of plant species, including a number of ornamental glasshouse crops. Recently in Europe, ornamental rose plants for the production of cut flowers and propagation materials have been strongly affected by Ralstonia pseudosolanacearum, phylotype I, biovar 3. To test for the presence of the pathogen in the glasshouse, sampling of water from a drainage gutter or well may be an efficient strategy since it is known that RSSC can be released from infected root systems in the water. A protocol was developed to detect low densities of R. pseudosolanacearum in drain water collected from rose growers. Drain water was filtered through a bacterial filter, the filtrate was collected and target bacteria enriched for 48 h in Semi‐selective Medium South Africa (SMSA) broth supplemented with sterilized tomato plant extracts. DNA extracted from the enrichment broth was analysed using a TaqMan test in a duplex format, based on specific egl sequences of RSSC and the use of an extraction and amplification control. The optimized protocol had a detection level of ≤1–10 colony forming units of R. pseudosolanacearum in drain water.

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Competition during enrichment of pathogenicEscherichia colimay result in culture bias

Cited by 16 publications

References 28 publications

Multi-Year Persistence of Verotoxigenic Escherichia coli (VTEC) in a Closed Canadian Beef Herd: A Cohort Study

Multi-Year Persistence of Verotoxigenic Escherichia coli (VTEC) in a Closed Canadian Beef Herd: A Cohort Study

Air-Dried Brown Seaweed, Ascophyllum nodosum , Alters the Rumen Microbiome in a Manner That Changes Rumen Fermentation Profiles and Lowers the Prevalence of Foodborne Pathogens

Detection of Ralstonia pseudosolanacearum in drain water based on concentration, enrichment and the use of a duplex TaqMan PCR test

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