COMPARISON OF PREVALENCE AND GENETIC DIVERSITY OF ESCHERICHIA COLI O157:H7 IN CATTLE AND SHEEP

ABSTRACT We compared the magnitude and duration of fecal shedding of wild-type Escherichia coli O157:H7 to that of an isogenic intimin mutant in young adult cattle and sheep. In both ruminant species, wild-type E. coli O157:H7 was shed in greater numbers and for a longer duration than was the intimin mutant.

Download Full-text

Greater Diversity of Shiga Toxin-Encoding Bacteriophage Insertion Sites among Escherichia coli O157:H7 Isolates from Cattle than in Those from Humans

Applied and Environmental Microbiology ◽

10.1128/aem.01035-06 ◽

2006 ◽

Vol 73 (3) ◽

pp. 671-679 ◽

Cited By ~ 86

Author(s):

Thomas E. Besser ◽

Nurmohammad Shaikh ◽

Nicholas J. Holt ◽

Phillip I. Tarr ◽

Michael E. Konkel ◽

...

Keyword(s):

Escherichia Coli ◽

Genetic Diversity ◽

Shiga Toxin ◽

Insertion Site ◽

Reservoir Host ◽

Clinical Isolates ◽

Escherichia Coli O157 ◽

Human Pathogen ◽

E Coli ◽

Insertion Sites

ABSTRACT Escherichia coli O157:H7, a zoonotic human pathogen for which domestic cattle are a reservoir host, produces a Shiga toxin(s) (Stx) encoded by bacteriophages. Chromosomal insertion sites of these bacteriophages define three principal genotypes (clusters 1 to 3) among clinical isolates of E. coli O157:H7. Stx-encoding bacteriophage insertion site genotypes of 282 clinical and 80 bovine isolates were evaluated. A total of 268 (95.0%) of the clinical isolates, but only 41 (51.3%) of the bovine isolates, belonged to cluster 1, 2, or 3 (P < 0.001). Thirteen additional genotypes were identified in isolates from both cattle and humans (four genotypes), from only cattle (seven genotypes), or from only humans (two genotypes). Two other markers previously associated with isolates from cattle or with clinical isolates showed similar associations with genotype groups within bovine isolates; the tir allele sp-1 and the Q 933W allele were under- and overrepresented, respectively, among cluster 1 to 3 genotypes. Stx-encoding bacteriophage insertion site typing demonstrated that there is broad genetic diversity of E. coli O157:H7 in the bovine reservoir and that numerous genotypes are significantly underrepresented among clinical isolates, consistent with the possibility that there is reduced virulence or transmissibility to humans of some bovine E. coli O157:H7 genotypes.

Download Full-text

Escherichia coli O157 in cattle and sheep at slaughter, on beef and lamb carcasses and in raw beef and lamb products in South Yorkshire, UK

International Journal of Food Microbiology ◽

10.1016/s0168-1605(00)00453-0 ◽

2001 ◽

Vol 64 (1-2) ◽

pp. 139-150 ◽

Cited By ~ 137

Author(s):

P.A Chapman ◽

A.T Cerdán Malo ◽

M Ellin ◽

R Ashton ◽

M.A Harkin

Keyword(s):

Escherichia Coli ◽

Escherichia Coli O157 ◽

Cattle And Sheep

Download Full-text

Genetic Diversity among Escherichia coli O157:H7 Isolates and Identification of Genes Linked to Human Infections

Infection and Immunity ◽

10.1128/iai.00956-07 ◽

2007 ◽

Vol 76 (2) ◽

pp. 845-856 ◽

Cited By ~ 12

Author(s):

Guanghui Wu ◽

Ben Carter ◽

Muriel Mafura ◽

Ernesto Liebana ◽

Martin J. Woodward ◽

...

Keyword(s):

Escherichia Coli ◽

Genetic Diversity ◽

Comparative Genomic ◽

Escherichia Coli O157 ◽

Microarray Hybridization ◽

E Coli ◽

Genomic Microarray ◽

K 12 ◽

Human Infections ◽

Dominant Genes

ABSTRACT An Escherichia coli oligonucleotide microarray based on three sequenced genomes was validated for comparative genomic microarray hybridization and used to study the diversity of E. coli O157 isolates from human infections and food and animal sources. Among 26 test strains, 24 (including both Shiga toxin [Stx]-positive and -negative strains) were found to be related to the two sequenced E. coli O157:H7 strains, EDL933 and Sakai. However, these strains showed much greater genetic diversity than those reported previously, and most of them could not be categorized as either lineage I or II. Some genes were found more often in isolates from human than from nonhuman sources; e.g., ECs1202 and ECs2976, associated with stx2AB and stx1AB, were in all isolates from human sources but in only 40% of those from nonhuman sources. Some (but not all) lineage I-specific or -dominant genes were also more frequently associated with isolates from human. The results suggested that it might be more effective to concentrate our efforts on finding markers that are directly related to infection rather than those specific to certain lineages. In addition, two Stx-negative O157 cattle isolates (one confirmed to be H7) were significantly different from other Stx-positive and -negative E. coli O157:H7 strains and were more similar to MG1655 in their gene content. This work demonstrates that not all E. coli O157:H7 strains belong to the same clonal group, and those that were similar to E. coli K-12 might be less virulent.

Download Full-text