Molecular analysis as an aid to assess the public health risk of non-O157 Shiga toxin-producing Escherichia coli strains.
Shiga toxin-producing Escherichia coli (STEC) strains are commensal bacteria in cattle with high potential for environmental and zoonotic transmission to humans. Although O157:H7 is the most common STEC serotype, there is growing concern over the emergence of more than 200 highly virulent non-O157 STEC serotypes that are globally distributed, several of which are associated with outbreaks and/or severe human illness such as hemolytic-uremic syndrome (HUS) and hemorrhagic colitis. At present, the underlying genetic basis of virulence potential in non-O157 STEC is unknown, although horizontal gene transfer and the acquisition of new pathogenicity islands are an expected origin. We used seropathotype classification as a framework to identify genetic elements that distinguish non-O157 STEC strains posing a serious risk to humans from STEC strains that are not associated with severe and epidemic disease. We report the identification of three genomic islands encoding non-LEE effector (nle) genes and 14 individual nle genes in non-O157 STEC strains that correlate independently with outbreak and HUS potential in humans. The implications for transmissible zoonotic spread and public health are discussed. These results and methods offer a molecular risk assessment strategy to rapidly recognize and respond to non-O157 STEC strains from environmental and animal sources that might pose serious public health risks to humans.
Coombes
Brian K
BK
Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre 4H17, 1200 Main St. West, Hamilton, Ontario L8N 3Z5, Canada. coombes@mcmaster.ca
Wickham
Mark E
ME
Mascarenhas
Mariola
M
Gruenheid
Samantha
S
Finlay
B Brett
BB
Karmali
Mohamed A
MA
D000818:Animals; D003106:Colon / Q000382:microbiology; D004927:Escherichia coli Infections / Q000175:diagnosis*; D005798:Genes, Bacterial; D044404:Genomic Islands / Q000235:genetics* / Q000502:physiology; D006463:Hemolytic-Uremic Syndrome / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D011634:Public Health; D022603:Shiga Toxins / Q000096:biosynthesis; D054323:Shiga-Toxigenic Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D037521:Virulence Factors / Q000235:genetics*
D022603:Shiga Toxins; D037521:Virulence Factors