Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: 7/9/1998
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: This study was conducted to determine if a PCR procedure previously developed for identification of Mycobacterium bovis in formalin-fixed tissues could also be used to identify mycobacteria of the M. avium complex. Two M. avium subspecies, avium and paratuberculosis, can cause tuberculosis-like lesions, so PCR identification of these organisms would be helpful for rapid differential diagnosis. Tissues were examined from 86 cases of M. avium infection (subspecies unknown) and from 14 additional cases identified as subspecies paratuberculosis infection by further culture characterization. Each tissue was tested with 5 different M. avium primers. Successful PCR identification depended on the primers used and the animal species tested. Primers for a ribosomal RNA(rRNA) gene were clearly the most efficient because they reacted with all of the 61 samples that reacted with any other primer set. The overall detection rate was 71 percent, being highest in avian tissue, 89 percent, followed by swine, 72 percent, and lastly ruminants, 57 percent (one elk sample was found to be an M. bovis infection). None of the avian or swine tissues reacted with primers for IS900 or hspX, which identify subspecies paratuberculosis. In contrast, 7 of 12 rRNA-positive ruminant samples reacted with these primers (6 with both and an additional sample with IS900 only). All 14 cases of culture-positive paratuberculosis infection were positive with the IS900 primers, whereas only 11 were positive by rRNA. We conclude that rRNA primers are the most useful for PCR identification of M. avium in formalin-fixed tissues of non-ruminant species. However, IS900 primers should also be used for ruminant tissues, because they are more sensitive for detection of subspecies paratuberculosis infections.