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when kits are used, difficulties in accurate identification often arise in testing facilities with little experience or in animal facilities with small scale testing.

In one facility in a medical school where P. pneumotropica was listed in the quarantine protocol for the barrier facility, tests were performed by PCR because of difficulty in identification by the conventional method. A swab from the conjunctiva was cultured in a liquid medium for bacterial growth, and the specific sequence of 16SrDNA of this organism was then detected by PCR. This method was used for quarantine because good results had been obtained in an experimental study and live animals could be tested. However, when the method was used in actual quarantine, the number of positive animals immediately increased and the introduction of new animals became difficult. When we tested some of the animals that were positive in the first test, we obtained consistently negative results. It is evident that results of bacteriologic tests using cultures will show discrepancies if there are differences in sampling sites, test methods, and identification criteria.

We also have encountered prolems in antibody testing, which we use for microbiologic monitoring of laboratory animals. The ICLAS Monitoring Center typically uses enzyme-linked immunosorbent assay (ELISA) as a screening test followed by the indirect immunofluorescent antibody (IFA) test or another method (such as the immunoblot method, hemagglutination inhibition test, or neutralization test) on serum suspected of being positive. When the sample is positive in both tests, it is evaluated as positive.

Clostridium piliforme (Tyzzer's organism)

Tyzzer's disease, which is characterized by diarrhea, focal necrosis in the liver, or death, has recently occurred in rats and rabbits at several breeding facilities in Japan. Sporadic cases of laboratory animals positive for this organism have also appeared in Japan.

Because it is difficult to culture this organism, we commonly detect the infection by using an antibody test such as complement fixation (CF), IFA, or ELISA. Generally, in antibody tests on mice and rats, the CF method is less sensitive and results in many false negatives, whereas ELISA is very sensitive and seldom results in false-positive cases.

At the ICLAS General Assembly held in May 1999, it was reported that a breeder of laboratory animals who first obtained antibody-positive test results from a testing facility and destroyed the animals later learned that the test results were incorrect, which caused a major loss. We also had tested these sera and had obtained negative results, and I have heard that these samples were also found to be negative when tested by an American testing facility.

The ICLAS Monitoring Center distributes an ELISA antibody test kit for Tyzzer's disease. Serum samples suspected of being antibody positive are sent to the Center where a confirmation test using IFA is performed. According to the



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