Profiling Mycobacterium xenopi with restriction fragment length polymorphism of insertion element IS1395

The aim of the present study was to assess the usefulness of insertion element IS1395 for differentiation of Mycobacterium xenopi, an increasingly common opportunistic human pathogen.

Fifty-two isolates obtained from 51 patients in Poland in 1996, 1997, and 1999, were analyzed by IS1395 restriction fragment length polymorphism (RFLP), and their susceptibilities to 11 anti-tuberculosis drugs were also determined.

IS1395-associated banding patterns of the isolates were not highly polymorphic; the RFLP patterns displayed several bands in common. Nevertheless, 44 of the 52 isolates were clearly distinguishable from each other. Only eight strains (15.4%) occurred in four clusters of two identical clones, one of which comprised two isolates obtained from one patient with a 12-month interval. The remaining six patients with clustered strains showed no apparent epidemiologic links with the other patients from the same cluster, and they were most likely infected by the same environmental source. No noticeable difference in RFLP pattern or IS1395 copy number between drug-sensitive and drug-resistant strains was shown. A high proportion (84.6%) of strains resistant to at least one drug was found, and 7.7% were resistant to more than three drugs.

The stability and utility of IS1395 for further detailed epidemiological investigations of M. xenopi was confirmed and extended.