TY - JOUR
T1 - Differences in virulence among Escherichia coli O157:H7 strains isolated from humans during disease outbreaks and from healthy cattle
AU - Baker, Diane R.
AU - Moxley, Rodney A.
AU - Steele, Mike B.
AU - LeJeune, Jeffrey T.
AU - Christopher-Hennings, Jane
AU - Chen, Ding Geng
AU - Hardwidge, Philip R.
AU - Francis, David H.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2007/11
Y1 - 2007/11
N2 - Escherichia coli O157:H7 causes life-threatening outbreaks of diarrhea, hemorrhagic colitis, and hemolyticuremic syndrome in humans and significant economic loss in agriculture and could be a potential agent of bioterrorism. Although the prevalence of E. coli O157:H7 in cattle and other species with which humans have frequent contact is high, human infections are relatively uncommon, despite a low infectious dose. A plausible explanation for the low disease incidence is the possibility that not all strains are virulent in humans. If there are substantial differences in virulence among strains in nature, then human disease may select for high virulence. We used a gnotobiotic piglet model to investigate the virulence of isolates from healthy cattle and from humans in disease outbreaks and to determine the correlation between production of Shiga toxin 1 (Stx1) and Stx2 and virulence. Overall, E. coli O157:H7 strains isolated from healthy cattle were less virulent in gnotobiotic piglets than strains isolated from humans during disease outbreaks. The amount of Stx2 produced by E. coli O157:H7 strains correlated with strain virulence as measured by a reduction in piglet survival and signs of central nervous system disease due to brain infarction. The amount of Stx1 produced in culture was not correlated with the length of time of piglet survival or with signs of central nervous system disease. We suggest that disease outbreaks select for producers of high levels of Stx2 among E. coli O157:H7 strains shed by animals and further suggest that Stx1 expression is unlikely to be significant in human outbreaks.
AB - Escherichia coli O157:H7 causes life-threatening outbreaks of diarrhea, hemorrhagic colitis, and hemolyticuremic syndrome in humans and significant economic loss in agriculture and could be a potential agent of bioterrorism. Although the prevalence of E. coli O157:H7 in cattle and other species with which humans have frequent contact is high, human infections are relatively uncommon, despite a low infectious dose. A plausible explanation for the low disease incidence is the possibility that not all strains are virulent in humans. If there are substantial differences in virulence among strains in nature, then human disease may select for high virulence. We used a gnotobiotic piglet model to investigate the virulence of isolates from healthy cattle and from humans in disease outbreaks and to determine the correlation between production of Shiga toxin 1 (Stx1) and Stx2 and virulence. Overall, E. coli O157:H7 strains isolated from healthy cattle were less virulent in gnotobiotic piglets than strains isolated from humans during disease outbreaks. The amount of Stx2 produced by E. coli O157:H7 strains correlated with strain virulence as measured by a reduction in piglet survival and signs of central nervous system disease due to brain infarction. The amount of Stx1 produced in culture was not correlated with the length of time of piglet survival or with signs of central nervous system disease. We suggest that disease outbreaks select for producers of high levels of Stx2 among E. coli O157:H7 strains shed by animals and further suggest that Stx1 expression is unlikely to be significant in human outbreaks.
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U2 - 10.1128/AEM.00755-07
DO - 10.1128/AEM.00755-07
M3 - Article
C2 - 17890332
AN - SCOPUS:36649013030
VL - 73
SP - 7338
EP - 7346
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
SN - 0099-2240
IS - 22
ER -