COMPARISON OF A NEW INSERTION ELEMENT, IS1407, WITH ESTABLISHED MOLECULAR MARKERS FOR THE CHARACTERIZATION OF MYCOBACTERIUM-CELATUM

Genomic analyses of 18 Mycobacterium celatum strains obtained from dif ferent patients in three countries (United States, United Kingdom, and France) were performed; the methods used in this study were restricti on fragment length polymorphism (RFLP) analysis, pulsed-field gel elec trophoresis (PFGE) analysis, and PCR restriction analysis (PRA) of the hsp-65 gene. A new insertion sequence, IS1407 (GenBank accession no. X97307), belonging to the IS256 family, was identified in Ill. celatum type 1 strains and was characterized by sequencing. When a probe for Mycobacterium xenopi IS1395-like sequences was used, the RFLP analysis of M. celatum type 1 strains revealed that they contained three or fo ur copies of IS1407 in identical genomic positions, while this element was absent in all ill. celatum type 2 strains, PFGE performed with th ree different endonucleases revealed a unique large restriction fragme nt (LRF) pattern for M. celatum type 1 strains, whereas the LRF patter ns obtained for M. celatum type 2 strains were polymorphic. Moreover, PFGE of nondigested genomic DNA revealed extrachromosomal elements in M. celatum type 2. The type strain of M. celatum type 3 could not be d ifferentiated from M. celatum type 1 strains on the basis of the resul ts of the RFLP analysis, the PFGE analysis, and the PRA of IS1407. In this study we confirmed that M. celatum types 1 and 2 represent distin ct genomic clusters and that the molecular markers in Ill. celatum typ e 2 exhibit greater polymorphism than the molecular markers in M. cela tum type 1.