Rapid differentiation of Mycobacterium avium subsp avium and Mycobacterium avium subsp paratuberculosis by amplification of insertion element IS901

The aim of this study was to examine the specificity of primers designed to detect the insertion element IS901 commonly used in differentiation of Mycobacterium avium complex strains. This study shows that one of these primers non-specifically anneals to a sequence inside insertion element IS900, specific IS of M. avium subsp. paratuberculosis and to another sequence flanking this element. The resulting non-specific amplicon can be a product of amplification from some M. avium subsp. paratuberculosis strains and can simulate the presence of insertion element IS901 in these strains.. However size difference between specific and non-specific amplicons allows such false-positive results to be distinguished. In addition the single PCR allows a rapid and simple differentiation between IS901+ M. avium subsp. avium and M. avium subsp. paratuberculosis strains.