New probes used for IS<it>1245 </it>and IS<it>1311 </it>restriction fragment length polymorphism of <it>Mycobacterium avium </it>subsp. <it>avium </it>and <it>Mycobacterium avium </it>subsp. <it>hominissuis </it>isolates of human and animal origin in Norway

<p>Abstract</p> <p>Background</p> <p><it>Mycobacterium avium </it>is an environmental mycobacterium that can be divided into the subspecies <it>avium</it>, <it>hominissuis, paratuberculosis </it>and <it>silvaticum</it>. Some <it>M. avium </it>subspecies are opportunistic pathogens for animals and humans. They are ubiquitous in nature and can be isolated from natural sources of water, soil, plants and bedding material. Isolates of <it>M. avium </it>originating from humans (n = 37), pigs (n = 51) and wild birds (n = 10) in Norway were examined by IS<it>1245 </it>and IS<it>1311 </it>RFLP using new and specific probes and for the presence of IS<it>901 </it>and IS<it>Mpa1 </it>by PCR. Analysis and generation of a dendrogram were performed with the software BioNumerics.</p> <p>Results</p> <p>IS<it>1311 </it>RFLP provided clear results that were easy to interpret, while IS<it>1245 </it>RFLP generated more complex patterns with a higher discriminatory power. The combination of the two methods gave additional discrimination between isolates. All avian isolates except one were <it>M. avium </it>subsp. <it>avium </it>with two copies of IS<it>1311 </it>and one copy of IS<it>1245</it>, while the isolates of human and porcine origin belonged to <it>M. avium </it>subsp.<it>hominissuis</it>. The isolates from human patients were distributed randomly among the clusters of porcine isolates. There were few identical isolates. However, one isolate from a human patient was identical to a porcine isolate. Regional differences were detected among the porcine isolates, while there was no clustering of human isolates according to type of clinical symptoms or geographical location of the patient's home addresses.</p> <p>Conclusion</p> <p>The results demonstrate that a wide range of <it>M. avium </it>subsp.<it>hominissuis </it>are present in pigs and humans in Norway, and that some of these isolates are very similar. It remains to be determined whether humans are infected from pigs or if they are infected from common environmental sources.</p>