Identification procedure for Pasteurella pneumotropica in microbiologic monitoring of laboratory animals

Discrepancies have been recognized in the identification of Pasteurella pneumotropica between testing laboratories. To determine the causes of the differences and to propose a reliable identification procedure for P. pneumotropica, a working group was organized and 69 isolates identified or suspected as P. pneumotropica were collected from 8 laboratories in Japan. These isolates were examined by colony morphology, Gram-staining, the slide agglutination test using two antisera (ATCC35149 and MaR), two commercially available biochemical test kits (ID test, API20NE) and two primer sets of PCR tests (Wang PCR, CIEA PCR). The 69 isolates and two reference strains were divided into 10 groups by test results. No single procedure for P. pneumotropica identification was found. Among tested isolates, large differences were not observed by colony morphology and Gram-straining except for colony colors that depended on their biotypes. Sixty-eight out of 69 isolates were positive by the slide agglutination test using two antisera except for one isolate that tested with one antiserum. The ID test identified 61 out of 69 isolates as P. pneumotropica and there was no large difference from the results of CIEA PCR. From these results, we recommend the combination of colony observation, Gram-straining, the slide agglutination tests with two antisera and biochemical test using the ID test for practical and reliable identification of this organism.