Resumen de Comparison of different methods for diagnosis of bovine tuberculosis from tuberculin‐ or interferon‐γ‐reacting cattle in Spain
César B. Gutiérrez Martín, L. Domínguez Rodríguez, Óscar Roberto González Llamazares, Elías Fernando Rodríguez Ferri, A. Aranaz Martín, Ernesto Liébana Criado
Of 1479 cattle from herds in Northwestern Spain previously diagnosed as tuberculosis (TB) positive, 218 animals which gave a positive tuberculin or interferon‐γ reaction were examined at the slaughterhouse. Medial retropharyngeal and caudal mediastinal lymph nodes, and any tissues containing lesions suspected to be tuberculous, were removed and submitted to the laboratory. Three techniques for diagnosis of TB were used: post mortem examination (PME), smear staining by means of auramine O method (AOM), and culture isolation in Coletsos and Lowenstein‐Jensen media followed by confirmation of M. tuberculosis complex organisms using PCR (CIM‐PCR). Only 123 (29·9%) of the 412 samples collected showed typical tuberculous lesions. Confirmed M. tuberculosis complex organisms were isolated in 144 cases, 114 of which were from tissues showing lesions (success rate of 92·8%). Smears were found positive in 113 cases, 96 of which came from lesions suspected to be tuberculous (success rate of 78·0%). The sensitivities of CIM‐PCR compared with those of PME and AOM were 92·7% and 85·7%, respectively. Statistical analysis revealed that PME and AOM are good indicators of the presence of M. tuberculosis complex organisms in tuberculin‐ or interferon‐γ reacting cattle.
