Polymerase chain reaction based detection of Mycobacterium tuberculosis IS6110 in cattle faeces

PCR amplification of insertion element IS6110 of Mycobacterium tuberculosis in fecal samples was evaluated in the diagnosis of intestinal tuberculosis (ITB). Single intradermal tuberculin test was carried in 125 cattle from organized dairy farms, off which, 36 animals gave a positive reaction. Blood and faecal samples were collected from all the tuberculin positive (36) animals. Demonstration of acid fast bacilli was done in the faecal samples by using the Ziehl - Neelsen staining. DNA was extracted and PCR was carried out in the blood and faecal samples by using IS6110 insertion sequence. Acid fast bacilli were observed in 10 (27.77%) faecal smears whereas, 18 (50%) faecal samples and 4 (11.11%) blood samples were found positive for the insertion sequence IS6110 of Mycobacterium tuberculosis complex. This result shows that IS6110 insertion sequence-PCR assay may be applied to detect tuberculous bacilli directly from faecal sample of dairy cows and therefore could be a valuable diagnostic or screening test for herds.