Molecular typing of Mycobacterium intracellulare using multilocus variable-number of tandem-repeat analysis: identification of loci and analysis of clinical isolates

1 Department of Clinical Research, National Hospital Organization, Higashinagoya National Hospital, 5-101 Umemorizaka, Meito-ku, Nagoya, Aichi 465-8620, Japan 2 Department of Pulmonary Medicine, National Hospital Organization, Higashinagoya National Hospital, 5-101 Umemorizaka, Meito-ku, Nagoya, Aichi 465-8620, Japan 3 Department of Infectious Diseases, Center of National University Hospital for Infection Control, Nagoya University Hospital, 65 Tsurumai, Showa-ku, Nagoya, Aichi 464-8560, Japan 4 Department of Microbiology, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya, Aichi 468-8503, Japan 5 Department of Pharmacy, National Hospital Organization, Nagoya Medical Center, 4-1-1 Sannomaru, Naka-ku, Nagoya 460-0001, Japan In addition to its known status as a disseminated disease in HIV-positive patients, Mycobacterium avium complex (MAC) is increasingly recognized as a causative pathogen of respiratory disease in HIV-negative patients. MAC is divided into Mycobacterium avium , and the less-epidemiologically studied Mycobacterium intracellulare . Genetic typing for M. intracellulare using variable number of tandem repeats (VNTR) has not yet been developed. The aim of this study was to identify VNTR loci in the genome of M. intracellulare and apply them as an epidemiological tool to clinical isolates. Here, we identified 25 VNTR loci on the M. intracellulare genome, of which 16 showed variations among clinical isolates in the number of tandem repeat motifs. Among the 74 M. intracellulare isolates, 50 genotypes were distinguished using the 16 VNTR loci, resulting in a Hunter Gaston's discriminatory index of 0.988. Moreover, all 16 VNTR loci were stable in different sets of isolates recovered within time intervals ranging from 2 to 1551 days from 14 separate patients. These results indicate that for use as epidemiological markers of M. intracellulare , the loci in this VNTR assay are highly discriminating and stable over time. Correspondence Kenji Ogawa ogawak{at}toumei.hosp.go.jp Abbreviations: MAC, Mycobacterium avium complex; MLVA, multilocus variable number of tandem repeats analysis; PRA, PCR-restriction enzyme analysis; TR, tandem repeat; VNTR, variable number of tandem repeats The DDBJ accession number for the sequence reported in this paper is AB519649. Three supplementary figures are available with the online version of this paper.