to a study from Scotland,
"Recent research has established that the terminal rectum is the
predominant colonization site of enterohemorrhagic
Escherichia coli O157:H7 in cattle. The main aim of the present work
was to investigate pathological changes and associated immune responses at
this site in animals colonized with E. coli O157:H7."
and gastrointestinal samples from a total of 22 weaned Holstein-cross
calves challenged with E. coli O157:H7 were analyzed for
bacterial colonization and pathology. Five unexposed age-matched calves
were used as comparative negative controls. E. coli O157:H7
bacteria induced histopathological alterations of
the rectal mucosa with enterocyte remodeling.
This was often associated with removal of the colonized epithelial layer. Immunogold labeling and transmission electron
microscopy (TEM) showed E. coli O157 bacteria on pedestals,
as part of attaching and effacing lesions. These pathological changes
induced a local infiltration of neutrophils that
was quantified as larger in infected animals. Rectal mucosal immunoglobulin
A responses were detected against the E. coli O157:H7
antigen," wrote P. Nart and colleagues (see
researchers concluded: "This work presents evidence that E. coli
O157:H7 is not a commensal bacteria
in the bovine host and that the mucosal damage produced by E. coli
O157:H7 colonization of the terminal rectum induces a quantifiable innate
immune response and production of specific mucosal antibodies."
Nart and colleagues published their study in Infection
and Immunity (Responses of Cattle to Gastrointestinal Colonization by
Escherichia coli O157:H7. Infection and Immunity, 2008;76(11):5366-5372).
more information, contact J.C. Low, Animal Health Group, Sir Stephen Watson
Bldg, Bush Estate, Penicuik EH26 0PH, Midlothian, Scotland.
contact information for the journal Infection and Immunity is:
American Society Microbiology, 1752 N St.
NW, Washington, DC 20036-2904,
Escherichia coli, Gastroenterology, Infectious Disease, Pathology.
article was prepared by FDA Law Weekly editors from staff and other