Dataset Information

Genetic Analysis of Virulence Potential of Escherichia coli O104 Serotypes Isolated From Cattle Feces Using Whole Genome Sequencing.

ABSTRACT: Escherichia coli O104:H4, a Shiga toxin-producing hybrid pathotype that was implicated in a major foodborne outbreak in Germany in 2011, has not been detected in cattle. However, serotypes of O104, other than O104:H4, have been isolated from cattle feces, with O104:H7 being the most predominant. In this study, we investigated, based on whole genome sequence analyses, the virulence potential of E. coli O104 strains isolated from cattle feces, since cattle are asymptomatic carriers of E. coli O104. The genomes of ten bovine E. coli O104 strains (six O104:H7, one O104:H8, one O104:H12, and two O104:H23) and five O104:H7 isolated from human clinical cases were sequenced. Of all the bovine O104 serotypes (H7, H8, H12, and H23) that were included in the study, only E. coli O104:H7 serotype possessed Shiga toxins. Four of the six bovine O104:H7 strains and one of the five human strains carried stx1c. Three human O104 strains carried stx2, two were of subtype 2a, and one was 2d. Genomes of stx carrying bovine O104:H7 strains were larger than the stx-negative strains of O104:H7 or other serotypes. The genome sizes were proportional to the number of genes carried on the mobile genetic elements (phages, prophages, transposable elements and plasmids). Both bovine and human strains were negative for intimin and other genes associated with the type III secretory system and non-LEE encoded effectors. Plasmid-encoded virulence genes (ehxA, epeA, espP, katP) were also present in bovine and human strains. All O104 strains were negative for antimicrobial resistance genes, except one human strain. Phylogenetic analysis indicated that bovine E. coli O104 strains carrying the same flagellar antigen clustered together and STEC strains clustered separately from non-STEC strains. One of the human O104:H7 strains was phylogenetically closely related to and belonged to the same sequence type (ST-1817) as the bovine O104:H7 STEC strains. This suggests that the bovine feces could be a source of human illness caused by E. coli O104:H7 serotype. Because bovine O104:H7 strains carried virulence genes similar to human clinical strains and one of the human clinical strains was phylogenetically related to bovine strains, the serotype has the potential to be a diarrheagenic pathogen in humans.

SUBMITTER: Shridhar PB

PROVIDER: S-EPMC5838399 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Genetic Analysis of Virulence Potential of Escherichia coli O104 Serotypes Isolated From Cattle Feces Using Whole Genome Sequencing.

Shridhar Pragathi B PB Patel Isha R IR Gangiredla Jayanthi J Noll Lance W LW Shi Xiaorong X Bai Jianfa J Elkins Christopher A CA Strockbine Nancy A NA Nagaraja T G TG

Frontiers in microbiology 20180301

Escherichia coli O104:H4, a Shiga toxin-producing hybrid pathotype that was implicated in a major foodborne outbreak in Germany in 2011, has not been detected in cattle. However, serotypes of O104, other than O104:H4, have been isolated from cattle feces, with O104:H7 being the most predominant. In this study, we investigated, based on whole genome sequence analyses, the virulence potential of E. coli O104 strains isolated from cattle feces, since cattle are asymptomatic carriers o ...[more]

PMID: 29545780

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Project description:Escherichia coli O145 serogroup is one of the big six non-O157 Shiga toxin producing E. coli (STEC) that causes foodborne illnesses in the United States and other countries. Cattle are a major reservoir of STEC, which harbor them in their hindgut and shed in the feces. Cattle feces is the main source of hide and subsequent carcass contaminations during harvest leading to foodborne illnesses in humans. The objective of our study was to determine the virulence potential of STEC O145 strains isolated from cattle feces and hide samples. A total of 71 STEC O145 strains isolated from cattle feces (n = 16), hide (n = 53), and human clinical samples (n = 2) were used in the study. The strains were subjected to whole genome sequencing using Illumina MiSeq platform. The average draft genome size of the fecal, hide, and human clinical strains were 5.41, 5.28, and 5.29 Mb, respectively. The average number of genes associated with mobile genetic elements was 260, 238, and 259, in cattle fecal, hide, and human clinical strains, respectively. All strains belonged to O145:H28 serotype and carried eae subtype γ. Shiga toxin 1a was the most common Shiga toxin gene subtype among the strains, followed by stx2a and stx2c. The strains also carried genes encoding type III secretory system proteins, nle, and plasmid-encoded virulence genes. Phylogenetic analysis revealed clustering of cattle fecal strains separately from hide strains, and the human clinical strains were more closely related to the hide strains. All the strains belonged to sequence type (ST)-32. The virulence gene profile of STEC O145 strains isolated from cattle sources was similar to that of human clinical strains and were phylogenetically closely related to human clinical strains. The genetic analysis suggests the potential of cattle STEC O145 strains to cause human illnesses. Inclusion of more strains from cattle and their environment in the analysis will help in further elucidation of the genetic diversity and virulence potential of cattle O145 strains.

Project description:Escherichia coli O104:H4, a hybrid pathotype reported in a large 2011 foodborne outbreak in Germany, has not been detected in cattle feces. However, cattle harbor and shed in the feces other O104 serotypes, particularly O104:H7, which has been associated with sporadic cases of diarrhea in humans. The objective of our study was to assess the virulence potential of Shiga toxin-producing E. coli (STEC) O104:H7 isolated from feces of feedlot cattle using DNA microarray. Six strains of STEC O104:H7 isolated from cattle feces were analyzed using FDA-E. coli Identification (ECID) DNA microarray to determine their virulence profiles and compare them to the human strains (clinical) of O104:H7, STEC O104:H4 (German outbreak strain), and O104:H21 (milk-associated Montana outbreak strain). Scatter plots were generated from the array data to visualize the gene-level differences between bovine and human O104 strains, and Pearson correlation coefficients (r) were determined. Splits tree was generated to analyze relatedness between the strains. All O104:H7 strains, both bovine and human, similar to O104:H4 and O104:H21 outbreak strains were negative for intimin (eae). The bovine strains were positive for Shiga toxin 1 subtype c (stx1c), enterohemolysin (ehxA), tellurite resistance gene (terD), IrgA homolog protein (iha), type 1 fimbriae (fimH), and negative for genes that code for effector proteins of type III secretory system. The six cattle O104 strains were closely related (r = 0.86-0.98) to each other, except for a few differences in phage related and non-annotated genes. One of the human clinical O104:H7 strains (2011C-3665) was more closely related to the bovine O104:H7 strains (r = 0.81-0.85) than the other four human clinical O104:H7 strains (r = 0.75-0.79). Montana outbreak strain (O104:H21) was more closely related to four of the human clinical O104:H7 strains than the bovine O104:H7 strains. None of the bovine E. coli O104 strains carried genes characteristic of E. coli O104:H4 German outbreak strain and unlike other human strains were also negative for Shiga toxin 2. Because cattle E. coli O104:H7 strains possess stx1c and genes that code for enterohemolysin and a variety of adhesins, the serotype has the potential to be a diarrheagenic foodborne pathogen in humans.

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Dataset Information

Genetic Analysis of Virulence Potential of Escherichia coli O104 Serotypes Isolated From Cattle Feces Using Whole Genome Sequencing.

Publications

Genetic Analysis of Virulence Potential of <i>Escherichia coli</i> O104 Serotypes Isolated From Cattle Feces Using Whole Genome Sequencing.

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