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Journal of Clinical Microbiology, Nov 1995, 2968-2972, Vol 33, No. 11
B Shames, JG Fox, F Dewhirst, L Yan, Z Shen and NS Taylor
The identification of a new murine pathogen, Helicobacter hepaticus, and
its association with chronic active hepatitis and liver tumors prompted an
evaluation of the prevalence of H. hepaticus in commercially available
mice. Of the 28 different strains or stocks, totaling 160 mice from four
major commercial vendors, cultured for H. hepaticus, 100% of mice from two
outbred strains from one vendor were infected with H. hepaticus, whereas 9
of 13 inbred mouse strains from another vendor were infected. This high
prevalence of H. hepaticus established a need for a rapid and reproducible,
noninvasive assay for the screening of colony-maintained mice being used
for biomedical research. The culturing of fecal material by using
0.45-microns-pore- size filtration for H. hepaticus consistently yielded
reproducible results but required extended periods of time. (1 to 3 weeks)
to obtain a definitive answer. Although it is rapid, the use of a direct
PCR- based detection assay with fecal specimens is restricted by inhibitory
agents. to circumvent these inhibitory agents and to augment our H.
hepaticus culture technique, we have developed a novel PCR system in which
the bacteria are isolated from fecal material in the presence of
polyvinylpyropyrollidone and lysed by treatment with Chelex 100. The PCR is
performed with Tth polymerase supplemented with a polymerase enhancer. By
this PCR method, 24 H. hepaticus culture-positive and 30 H. hepaticus
culture-negative fecal samples were correctly identified. Moreover, two
samples which were PCR positive and culture negative initially were
positive by both methods upon retesting of fresh material. Southern blot
hybridizations and sequencing of PCR products showed them to be H.
hepaticus specific. A comparison of results obtained under identical
conditions indicated a 100-fold increase in sensitivity with Tth polymerase
over Taq polymerase. This PCR method can be used as a noninvasive means of
rapidly screening large numbers of colony mice for H. hepaticus.
Copyright © 1995 by the American Society for Microbiology. All rights reserved.
Identification of widespread Helicobacter hepaticus infection in feces in commercial mouse colonies by culture and PCR assay
Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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