LARGE-RESTRICTION-FRAGMENT ANALYSIS OF MYCOBACTERIUM-KANSASII GENOMICDNA AND ITS APPLICATION IN MOLECULAR TYPING

Large-restriction-fragment (LRF) polymorphisms in Mycobacterium kansas ii isolates from 84 patients with bronchopulmonary infections in Japan between the 1960s and 1995 were studied by pulsed-field gel electroph oresis (PFGE). Chromosomal fragments digested with VspI were most suit able for PFGE separation of 16 to 21 fragments of between 40 and 550 k bp. All 84 isolates and the type strain M. kansasii ATCC 12478 were su ccessfully typed by LRF analysis with VspI digestion. Twenty-one disti nctive LRF types were identified, and the LRF patterns tested over tim e were reproducible and stable. A computer-assisted dendrogram of the percent similarity demonstrated that isolates of 18 LRF types had rela tively close genetic relatedness, while isolates of the remaining 3 ty pes showed divergence. Sequence analysis of the 16S rRNA gene in the i solates showing divergent genetic relatedness revealed a sequence iden tical to that of a previously reported subspecies of M. kansasii. In t he Chugoku district of Japan, 11 cases of M. kansasii infection which occurred in workers in a coastal industrial zone between 1982 and 1993 were caused by one particular strain tentatively named LRF type M. Wh en both detailed demographic data for the patients and ecologic data f or the M. kansasii isolates are obtained, LRF typing may be of potenti al use for investigating the source and transmission of M. kansasii in fection.