|Jenny, Allen - USDA-APHIS-NVSL,AMES,IA|
|Rhyan, Jack - USDA-APHIS-NVSL,AMES,IA|
|Saari, Dennis - USDA-APHIS-NVSL, AMES, IA|
Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: October 12, 1996
Publication Date: N/A
Technical Abstract: An important part of the USDA surveillance program for tuberculosis relies on detection of the causative organism, Mycobacterium bovis, in tissues of suspect animals that are taken at the time of slaughter. The presence of characteristic histopathologic lesions is adequate for a presumptive diagnosis, but definitive diagnosis requires culture and species identification of the bacterium. Unfortunately, the latter process usually takes several weeks. The purpose of work reported here was to evaluate whether the polymerase chain reaction (PCR) technique could be used on formalin-fixed paraffin-embedded tissues to provide a more rapid diagnosis of tuberculosis. Primers used for the PCR test amplified a 123 bp fragment of IS 6110, an insertion sequence specific for mycobacteria in the M. tuberculosis complex (M. tuberculosis, M. bovis, M. microti, M. africanum). To test efficiency of the PCR procedure, paraffin sections of nondecalcified tissues from 99 cases of tuberculosis were examined. Previous histopathologic examinations had shown that all of the tissues had typical lesions of tuberculosis and contained acid-fast bacteria. In addition, diagnostic records indicated that M. bovis was cultured from each case. Results of the PCR test were positive in 92 (93%) of the samples. Specificity of the test was demonstrated by negative results in 31 tissues that had either nonmycobacterial granulomas or granulomatous lesions caused by M. paratuberculosis or M. avium. These results show that most cases of tuberculosis can be diagnosed within 2-3 days through application of the PCR technique to paraffin sections of suspect lesions.