[Present status of studies on epidemiology and molecular epidemiology of Mycobacterium kansasii, in special reference...

There appears to be some genetic diversity among Mycobacterium kansasii (M. kansasii) isolates recovered throughout the world. Restriction analysis of heat shock protein 65-polymerase chain reaction-restriction analysis (hsp65PRA) showed that M. kansasii contains seven subspecies genetically distinct from M. kansasii isolates. M. kansasii genotype I is predominant in Japan and shows a very tight clonal structure. Different molecular typing methods including the 16S-23S rRNA spacer (ITS) region, RFLP, and PFGE analysis have been applied to isolates worldwide, and M. kansasii genotype I, as defined by hsp65PRA, appears to be highly clonal and the most common genotype associated with human disease. However, the identification of M. kansasii at the subtype level may possibly be more than just an interesting epidemiological tool; it may be relevant to determining the infectious pathway and clinical management of individual cases, as it allows the differentiation of potentially pathogenic subtypes from nonpathogenic subtypes. This review has been followed by the first review of the epidemiology of M. kansasii, and summarizes the evidence of molecular epidemiology and establishes the validity and importance of studies of M. kansasii. Further, the more precise definition of various M. kansasii isolates herein should provide a significant contribution to the understanding of key aspects of its biology, genotype, and molecular epidemiology.