
DNA microarray-based assessment of virulence potential of Shiga toxin gene-carrying Escherichia coli O104:H7 isolated from feedlot cattle feces
Author(s) -
Pragathi B. Shridhar,
Isha R. Patel,
Jayanthi Gangiredla,
Lance Noll,
Xiaorong Shi,
Jianfa Bai,
Christopher Elkins,
Nancy Strockbine,
T. G. Nagaraja
Publication year - 2018
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0196490
Subject(s) - biology , microbiology and biotechnology , escherichia coli , virulence , feces , outbreak , shiga toxin , serotype , intimin , gene , virology , enterobacteriaceae , genetics
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 ( stx 1c), 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 stx 1c and genes that code for enterohemolysin and a variety of adhesins, the serotype has the potential to be a diarrheagenic foodborne pathogen in humans.