Performance of immunohistochemistry vs real-time PCR methods for detecting mycobacterial infections of cattle screened by comparative tuberculin test

In addition to the fifty years since the test-and-slaughter program began in Iran and despite a significant reduction in the disease prevalence, positive tuberculosis cases are still being isolated from livestock farms across the country. Tests with ۱۰۰% sensitivity and specificity are essential features for bovine tuberculosis diagnosis. The relationship between real-time PCR and immunohistochemistry (IHC) as two essential laboratory methods in the diagnosis of bacterial infections were aimed to evaluate single intradermal comparative tuberculin test (SICTT) results. One hundred thirty-eight cows in two groups were examined: Reactors (۱۰۸ cows) and clean (as a control group; ۳۰ cows). In the reactor group, ۵۸(۵۴.۰۰%) cows were Mycobacterium bovis positive, ۴۶(۴۳.۰۰%) were Mycobacterium avium subsp. paratuberculosis (MAP) positive, and ۱۱(۱۰.۰۰%) were Mycobacterium tuberculosis positive. ۳۲(۵۵.۰۰%) cows were co-infected with M. bovis and MAP and ۵(۴.۵۵%) cows were co-infected with Mycobacterium tuberculosis and MAP in this group. Of ۵۰ M. bovis negative cows of reactor group were ۱۴(۲۸.۰۰%) MAP positive and ۳۶(۷۲.۰۰%) negative, as well. Concurrent infection with all was observed in one reactor case. Comparing IHC and real-time PCR for the detection of bovine tuberculosis and Johne’s disease showed very good agreement (Kappa values ۰.۸۱ - ۱.۰۰). The results also provided further confirmation on IHC and real-time PCR as a sensitive and reliable diagnostic screening approach for detection of bovine tuberculosis. The use of one laboratory method to detect bovine tuberculosis is not sufficient alone.

کلیدواژه ها:

Immunohistochemistry ، mycobacterium ، Real-time PCR ، Tuberculin