CLOSTRIDIUM DIFFICILE INFECTION

The long term objective of this proposed research is to enhance our
understanding of spontaneous diarrhea caused by Clostridium difficile in
aged hamsters. The immediate objective is to study the host responses
of aged hamsters to experimental C. difficile infection and to the
exotoxins of this bacterium. There are 4 specific aims: (1) To study the
host responses of aged hamsters to C. difficile infection, (2) To compare
the efficacy of microbiological isolation and identification with that
of detection of toxin-A by enzyme immunoassay and toxin-B by tissue
culture cytotoxicity assay, (3) To study flora changes during C.
difficile infection and to explore the use of DNA hybridizational
technique as a tool for enumeration of predominant flora, and (4) To
study the host responses of aged hamsters to the exotoxins of C.
difficile. To achieve specific aim 1, 132 retired breeders of both sexes
will be used in 11 experimental groups to examine the susceptibility of
aged hamsters to varied doses of inciting antibiotic - clindamycin - and
simultaneous ingestion of C. difficile. The objective of specific aim
1 is to answer the question whether the same type of proliferative
caecitis and colitis can be reproduced experimentally. For specific aim
2, a comparison of 3 detection methods is proposed. The routine
microbiological isolation on CCFA agar, detection of toxin A by EIA and
detection of toxin B by cytotoxicity. This experiment will help us to
device better means of detection of C. difficile. For specific aim 3,
a novel approach in the enumeration of predominant flora is proposed.
A DNA hybridizational technique is used to estimate population level of
a predominant bacterial species, Bacteroides ovatus, in the ceca of
affected hamsters. And finally for specific aim 4, hamsters will be
injected intracecally and intravenously (portal vein) of both exotoxins
to produce the typical lesions in the ceca and to answer the question of
the relationship between cholangiohepatitis and glomerulonephritis to C.
difficile infection. The completion of these 4 experiments will provide
scientific data to enhance our understanding of the disease induced by
C. difficile and to device ways and means to limit the potential effects
of this disease on experiments that require the use of hamsters housed
for prolonged period in the laboratory.