A Survey of &amp;lt;i&amp;gt;Escherichia coli&amp;lt;/i&amp;gt; O157:H7  Virulence Factors: The First 25 Years and 13 Genomes

Reiland, Holly A.; Omolo, Morrine; Johnson, Timothy J.

doi:10.4236/aim.2014.47046

Cited by 14 publications

(22 citation statements)

References 107 publications

(198 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The hypotheses based on a “commensal” origin pertain to D6-117.07, P4, VL2732 and VL2874, which very likely belong to the mainly commensal A. By contrast, highly virulent O157:H7 strains are known to possess specific virulence factors, including toxins, molecules responsible of the formation of secretion systems, and molecules involved in attaching/effacing lesions [ 70 , 71 ]. Nevertheless, a specific search for candidate virulence genes showed that strain D6-113.11 was clearly different from the O157:H7 Sakai strain included in our comparison.…”

Section: Discussionmentioning

confidence: 99%

Genomic Comparative Study of Bovine Mastitis Escherichia coli

Kempf

Slugocki

Blum³

et al. 2016

PLoS ONE

View full text Add to dashboard Cite

Escherichia coli, one of the main causative agents of bovine mastitis, is responsible for significant losses on dairy farms. In order to better understand the pathogenicity of E. coli mastitis, an accurate characterization of E. coli strains isolated from mastitis cases is required. By using phylogenetic analyses and whole genome comparison of 5 currently available mastitis E. coli genome sequences, we searched for genotypic traits specific for mastitis isolates. Our data confirm that there is a bias in the distribution of mastitis isolates in the different phylogenetic groups of the E. coli species, with the majority of strains belonging to phylogenetic groups A and B1. An interesting feature is that clustering of strains based on their accessory genome is very similar to that obtained using the core genome. This finding illustrates the fact that phenotypic properties of strains from different phylogroups are likely to be different. As a consequence, it is possible that different strategies could be used by mastitis isolates of different phylogroups to trigger mastitis. Our results indicate that mastitis E. coli isolates analyzed in this study carry very few of the virulence genes described in other pathogenic E. coli strains. A more detailed analysis of the presence/absence of genes involved in LPS synthesis, iron acquisition and type 6 secretion systems did not uncover specific properties of mastitis isolates. Altogether, these results indicate that mastitis E. coli isolates are rather characterized by a lack of bona fide currently described virulence genes.

show abstract

Section: Discussionmentioning

confidence: 99%

Genomic Comparative Study of Bovine Mastitis Escherichia coli

Kempf

Slugocki

Blum³

et al. 2016

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…Interestingly, the major STEC genotype isolated from 12 months old calves was stx2 . Two stx genes encode Shiga toxins which are stx1AB and stx2AB , and it has been reported that Stx2 is associated with more severe human infections [ 20 , 21 ]. The predominance of stx2 genotype in older calves is noteworthy, although the overall STEC prevalence declined when animals aged, because Stx2 is 1000 times more toxic than Stx1 as shown previously in animal models [ 22 , 23 ].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, recent Shiga toxin producing E . coli O157:H7 outbreak strains have been found to carry two copies of the stx2AB gene cluster instead of one of the stx1AB and one of the stx2AB clusters each, making them more virulent than the isolates carrying only the stx1AB gene cluster, due to lack of competition for GB3 binding [ 20 , 21 ]. Taken together, although the prevalence of STEC was lower in older animals, the calves were carrying more pathogenic STEC, suggesting further STEC genotyping is necessary for proper risk assessment.…”

Section: Discussionmentioning

confidence: 99%

Colonization of Beef Cattle by Shiga Toxin-Producing Escherichia coli during the First Year of Life: A Cohort Study

et al. 2016

View full text Add to dashboard Cite

Each year Shiga toxin-producing Escherichia coli (STEC) are responsible for 2.8 million acute illnesses around the world and > 250,000 cases in the US. Lowering the prevalence of this pathogen in animal reservoirs has the potential to reduce STEC outbreaks in humans by controlling its entrance into the food chain. However, factors that modulate the colonization and persistence of STEC in beef cattle remain largely unidentified. This study evaluated if animal physiological factors such as age, breed, sex, and weight gain influenced the shedding of STEC in beef cattle. A cohort of beef calves (n = 260) from a multi-breed beef calf population was sampled every three months after birth to measure prevalence and concentration of STEC during the first year of life. Metagenomic analysis was also used to understand the association between the STEC colonization and the composition of gut microflora. This study identified that beef calves were more likely to shed STEC during the first 6 months and that STEC shedding decreased as the animal matured. Animal breed group, sex of the calf, and average weight gain were not significantly associated with STEC colonization. The metagenomic analysis revealed for the first time that STEC colonization was correlated with a lower diversity of gut microflora, which increases as the cattle matured. Given these findings, intervention strategies that segregate younger animals, more likely to be colonized by STEC from older animals that are ready to be harvested, could be investigated as a method to reduce zoonotic transmission of STEC from cattle to humans.

show abstract

“…The ability of E. coli O157:H7 to cause disease is associated with production of Shiga toxins, which is controlled by stx1 and stx2 genes and other virulence factors (Bai, Shi, & Nagaraja, 2010;Reiland, Omolo, Johnson, & Baumler, 2014). Moreover, culture conditions, such as temperature, acidic environment, and nutrient levels, can affect the expression of bacterial virulence genes (Allen et al, 2008;Yin et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Effects of lactic acid stress with lactic acid adaptation on the survival and expression of virulence‐related genes in Escherichia coli O157:H7

et al. 2019

Journal of Food Safety

View full text Add to dashboard Cite

This study was aimed to investigate the effects of lactic acid stress with acid adaptation on the survival and expression of virulence‐related genes in Escherichia coli O157:H7 (strains CICC21530, 89, 95, 112, 109, and J42). E. coli were subjected to acid adaption (pH 5.0) for 1–4 hr and then exposed to acid stress (pH 3.5) for 30–120 min. Results showed that exposure to pH 3.5 decreased the survival of E. coli strains, in which strains 109, 112, and J42 had stronger acid resistance. The expression of virulence‐related genes of most strains decreased after exposure to pH 3.5 compared with nonstressed cells. In addition, acid adaptation increased the acid resistance of most strains, except for CICC21530 and J42. And the virulence expression of most acid‐adapted cells decreased or showed no significant changes compared with nonadapted cells. There were no obvious relationships between the survival and expression of virulence‐related genes in E. coli O157:H7 strains. However, variable acid resistance of acid‐adapted strains was existed, and some acid adaptation increased the strain survival and expression of virulence‐related genes, which may still threaten food safety. Practical Applications This study evaluated the effects of lactic acid stress with acid adaptation on the survival and expression of virulence‐related genes in Escherichia coli O157:H7. Acid adaptation could enhance the survival and virulence expression of some strains, which will threaten the safety of acidic food during processing and storage. Furthermore, variable acid resistance of acid‐adapted strains should be noticed in surveillance and control of E. coli O157:H7 in environment and food, which is beneficial for its scientific and effective risk assessment and control.

show abstract

A Survey of <i>Escherichia coli</i> O157:H7 Virulence Factors: The First 25 Years and 13 Genomes

Cited by 14 publications

References 107 publications

Genomic Comparative Study of Bovine Mastitis Escherichia coli

Genomic Comparative Study of Bovine Mastitis Escherichia coli

Colonization of Beef Cattle by Shiga Toxin-Producing Escherichia coli during the First Year of Life: A Cohort Study

Effects of lactic acid stress with lactic acid adaptation on the survival and expression of virulence‐related genes in Escherichia coli O157:H7

Contact Info

Product

Resources

About