Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/11/1996
Publication Date: N/A
Technical Abstract: A presumptive diagnosis of tuberculosis is based on the finding of characteristic histopathologic lesions and acid-fast organisms in a tissue. A definitive diagnosis, however, requires culture and species identification of the causative mycobacterium, a process that usually takes several weeks to complete. The purpose of work reported here was to determine if formalin-fixed paraffin-embedded tissue could be tested by polymerase chain reaction (PCR) to provide a more rapid diagnosis of tuberculosis. Nondecalcified tissues from cases of tuberculosis in cattle and elk were examined. The primers used for PCR amplified a 123 bp fragment of IS6110, an insertion sequence that is specific for organisms in the M. tuberculosis complex (M. tuberculosis, M. bovis, M. microti, M. africanum). The sequence was detected in tissues from 92 of 99 (93%) tuberculosis cases, including 3 of 4 elk. In 80 of these cases the positive results were obtained using a simplified tissue extraction method that did not require paraffin removal, enzyme digestion or DNA purification. For detection of the other 12 cases, DNA purification was required. Accuracy of the IS6110 PCR test was demonstrated by negative test results on 31 tissues that had either nonmycobacterial granulomas or granulomatous lesions caused by other mycobacteria (M. paratuberculosis or M. avium). The findings of this study show that a PCR test usually will provide a rapid diagnosis of tuberculosis when it is applied to paraffin sections that have characteristic lesions and acid-fast organisms.