DNA microarray-based assessment of virulence potential of Shiga toxin gene-carrying Escherichia coli O104:H7 isolated from feedlot cattle feces

PLoS One. 2018 Apr 30;13(4):e0196490. doi: 10.1371/journal.pone.0196490. eCollection 2018.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adhesins, Bacterial / genetics
  • Animals
  • Cattle
  • Disease Outbreaks / veterinary
  • Escherichia coli Infections / epidemiology
  • Escherichia coli Infections / veterinary
  • Escherichia coli O104 / genetics*
  • Escherichia coli O104 / isolation & purification
  • Escherichia coli Proteins / genetics
  • Feces / microbiology
  • Genotype
  • Hemolysin Proteins / genetics
  • Humans
  • Models, Statistical
  • Oligonucleotide Array Sequence Analysis*
  • Phenotype
  • Phylogeny
  • Serotyping
  • Shiga Toxin / genetics*
  • Shiga Toxin 2 / genetics
  • Shiga-Toxigenic Escherichia coli / genetics*
  • Shiga-Toxigenic Escherichia coli / isolation & purification
  • Virulence / genetics

Substances

  • Adhesins, Bacterial
  • Escherichia coli Proteins
  • Hemolysin Proteins
  • Shiga Toxin 2
  • enterohemolysin
  • Shiga Toxin