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Shiga Toxin Subtypes of Non-O157 Escherichia coli Serogroups Isolated from Cattle Feces

Overview of attention for article published in Frontiers in Cellular and Infection Microbiology, April 2017
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Title
Shiga Toxin Subtypes of Non-O157 Escherichia coli Serogroups Isolated from Cattle Feces
Published in
Frontiers in Cellular and Infection Microbiology, April 2017
DOI 10.3389/fcimb.2017.00121
Pubmed ID
Authors

Pragathi B. Shridhar, Chris Siepker, Lance W. Noll, Xiaorong Shi, T. G. Nagaraja, Jianfa Bai

Abstract

Shiga toxin producing Escherichia coli (STEC) are important foodborne pathogens responsible for human illnesses. Cattle are a major reservoir that harbor the organism in the hindgut and shed in the feces. Shiga toxins (Stx) are the primary virulence factors associated with STEC illnesses. The two antigenically distinct Stx types, Stx1 and Stx2, encoded by stx1 and stx2 genes, share approximately 56% amino acid sequence identity. Genetic variants exist within Stx1 and Stx2 based on differences in amino acid composition and in cytotoxicity. The objective of our study was to identify the stx subtypes in strains of STEC serogroups, other than O157, isolated from cattle feces. Shiga toxin gene carrying E. coli strains (n = 192), spanning 27 serogroups originating from cattle (n = 170) and human (n = 22) sources, were utilized in the study. Shiga toxin genes were amplified by PCR, sequenced, and nucleotide sequences were translated into amino acid sequences using CLC main workbench software. Shiga toxin subtypes were identified based on the amino acid motifs that define each subtype. Shiga toxin genotypes were also identified at the nucleotide level by in silico restriction fragment length polymorphism (RFLP). Of the total 192 STEC strains, 93 (48.4%) were positive for stx1 only, 43 (22.4%) for stx2 only, and 56 (29.2%) for both stx1 and stx2. Among the 149 strains positive for stx1, 132 (88.6%) were stx1a and 17 (11.4%) were stx1c. Shiga toxin 1a was the most common subtype of stx1 among cattle (87.9%; 123/140) and human strains (100%; 9/9) of non-O157 serogroups. Of the total 99 strains positive for stx2, 79 were stx2a (79.8%), 11 (11.1%) were stx2c, 12 (12.1%) were stx2d. Of the 170 strains originating from cattle feces, 58 (34.1%) were stx2a subtype, 11 (6.5%) were stx2c subtype, and 11 were of subtype stx2d (6.5%). All but one of the human strains were positive for stx2a. Three strains of cattle origin were positive for both stx2a and stx2d. In conclusion, a number of non-O157 STEC serogroups harbored by cattle possess a wide variety of Shiga toxin subtypes, with stx1a and stx2a being the most predominant stx subtypes occurring individually or in combination. Cattle are a reservoir of a number of non-O157 STEC serogroups and information on the Shiga toxin subtypes is useful in assessing the potential risk as human pathogens.

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Mendeley readers

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Geographical breakdown

Country Count As %
Unknown 60 100%

Demographic breakdown

Readers by professional status Count As %
Student > Ph. D. Student 11 18%
Student > Master 11 18%
Student > Doctoral Student 5 8%
Professor > Associate Professor 5 8%
Professor 4 7%
Other 10 17%
Unknown 14 23%
Readers by discipline Count As %
Agricultural and Biological Sciences 10 17%
Veterinary Science and Veterinary Medicine 9 15%
Immunology and Microbiology 9 15%
Biochemistry, Genetics and Molecular Biology 6 10%
Unspecified 1 2%
Other 4 7%
Unknown 21 35%
Attention Score in Context

Attention Score in Context

This research output has an Altmetric Attention Score of 1. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 11 April 2017.
All research outputs
#20,413,129
of 22,963,381 outputs
Outputs from Frontiers in Cellular and Infection Microbiology
#6,029
of 6,463 outputs
Outputs of similar age
#270,218
of 310,113 outputs
Outputs of similar age from Frontiers in Cellular and Infection Microbiology
#142
of 155 outputs
Altmetric has tracked 22,963,381 research outputs across all sources so far. This one is in the 1st percentile – i.e., 1% of other outputs scored the same or lower than it.
So far Altmetric has tracked 6,463 research outputs from this source. They typically receive a little more attention than average, with a mean Attention Score of 5.3. This one is in the 1st percentile – i.e., 1% of its peers scored the same or lower than it.
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We're also able to compare this research output to 155 others from the same source and published within six weeks on either side of this one. This one is in the 1st percentile – i.e., 1% of its contemporaries scored the same or lower than it.