| Abstrakt: |
A PCR procedure previously developed for identification of Mycobacterium bovisin formalin-fixed tissues was used to identify mycobacteria of the M. aviumcomplex. Tissues were examined from 100 culture-positive cases of M. aviumcomplex infection, including 86 in which the subspecies was not identified and 14 that had been identified as M. aviumsubsp. paratuberculosis. Each sample was tested with 5 primer sets, 16S ribosomal RNA (rRNA), IS900, IS901, IS1245, and a heat shock protein (hspX), that detect 1 or both M. aviumsubspecies. The success rate of PCR detection varied with the primers used and the animal species tested. Among the 86 cases with no M. aviumsubspecies designation, primers for the 16S rRNA gene were clearly the most efficient because they produced amplicons from all samples that reacted with any other primer set. The overall detection rate in this group of samples was 71%: highest in avian tissues (89%) followed by swine (72%) and ruminants (57%) None of the avian or swine tissues reacted with primers for IS900or hspX, which identify M. a. paratuberculosis. In contrast, 7 of the 12 ruminant samples that were 16S rRNA positive reacted with 1 or both of these primers. All of the 14 cases shown by culture to be M. a. paratuberculosisinfections were positive with IS900primers, whereas only 11 were positive for 16S rRNA. These results indicate that 16S rRNA primers are the most useful for PCR identification of M. aviumin formalin-fixed tissues of nonruminant species. However, IS900primers should also be used when ruminant tissues are examined because these primers provide the greatest sensitivity for detection of M. a. paratuberculosisinfections. |
