Evaluation of three commercial PCR kits for the direct detection of Mycobacterium avium subsp. paratuberculosis (MAP) in bovine faeces

In total, 100 positive samples were tested which consisted of 25 high shedders, 25 medium shedders, 25 low shedders and 25 very low shedders. Also included were 100 negative faecal samples obtained from two Irish herds known to be free of Johne's disease. The kits evaluated in this study showed significant differences in identifying MAP DNA from animals shedding various concentrations of the bacterium. Kit C had the highest specificity, followed by kits B and A. Sensitivity in kits A, B and C was 73.5%, 81% and 93%, respectively, and specificity was 99%, 97% and 100%, respectively. Sensitivity decreased with lower concentrations of MAP in faeces but this was more significant for kits A and B than for kit C. The results of this study demonstrate that PCR can provide an accurate and rapid detection of MAP faecal shedding and kit C was selected for further evaluation of the role of PCR in the confirmation of animal infection in cattle.