Sensibilidad y especificidad de PCR anidada y Spoligotyping como pruebas rápidas de diagnóstico de tuberculosis bovina en tejido fresco

quick diagnosis of tuberculosis in cattle is critical to decide whether or not to quarantine or depopulate a herd. currently, decisions are based on culture, which takes between four and eight weeks to accomplish. therefore, the purpose of this study was to evaluate relative sensitivity and specificity of two pcr's (mpb70 and is6110) and spoligotyping as quick diagnostic tests for cattle tuberculosis in fresh tissue. fifty tissue samples with tb-suspicious lesions from a herd with 25 % prevalence of the disease and fifty tissue samples with no lesions from a tb-free herd were used in the study. samples were split into two sets and each set was blind analyzed in two different laboratories under the same protocol. the three tests were used to diagnose tuberculosis in all samples using macerated tissue just before culturing. relative sensitivity and specificity of all tests were estimated using presence/absence of lesion, histopathology and culture results as gold standards. mpb70 nested pcr showed consistently higher sensitivity (85 to 91 %) and specificity (77 to 86 %) in one of the laboratories with all gold standards; however, inter-laboratory differences occurred, in one of the laboratories sensitivity was from 89 to 91 % and specificity from 57 to 63 %. is6110 nested pcr and spoligotyping behaved poorly. relative sensitivity and specificity for mpb70 nested pcr suggest that this test could be useful as a complementary test for quick diagnosis of bovine tb in fresh tissue.