Korean isolates of the Mycobacterium chelonae-Mycobacterium abscessus group, which had been isolated from two different hospitals in South Korea, were identified by PCR restriction analysis (PRA) and comparative sequence analysis of 16S rRNA genes, rpoB, and hsp65 to evaluate the proportion of four closely related species (M. chelonae, M. abscessus, M. massiliense, and M. bolletii). Of the 144 rapidly growing mycobacterial strains tested, 127 strains (88.2%) belonged to the M. chelonae-M. abscessus group. In this group, M. chelonae, M. abscessus, M. massiliense, and M. bolletii accounted for 0.8% (n ‫؍‬ 1), 51.2% (n ‫؍‬ 65), 46.5% (n ‫؍‬ 59), and 1.6% (n ‫؍‬ 2), respectively. Two isolates which showed discordant results, M. massiliense by rpoB sequence analysis and M. abscessus by hsp65 sequence analysis, were finally identified as M. massiliense based on the additional analysis of sodA and the 16S-23S internal transcribed spacer. M. abscessus group I isolates previously identified by hsp65 PRA were all found to be M. abscessus, whereas group II isolates were further identified as M. massiliense or M. bolletii by sequencing of rpoB and hsp65. Smooth, rough, or mixed colonies of both M. abscessus and M. massiliense isolates were observed. M. massiliense strains that were highly resistant to clarithromycin had a point mutation at the adenine at position 2058 (A 2058 ) or 2059 (A 2059 ) in the peptidyltransferase region of the 23S rRNA gene.Rapidly growing mycobacteria (RGM), which include members of the Mycobacterium fortuitum complex, the M. chelonae complex, and the M. smegmatis complex, are defined as mycobacteria that grow and form visible colonies on solid agar media within 7 days. Because of their low virulence, they usually cause respiratory tract or disseminated infections in persons with predisposing factors or who are immunosuppressed (27,29,32). However, recently, infections in immunocompetent persons have been reported more frequently. These cases are soft-tissue infections associated with trauma and injection and epidemics or pseudoepidemics that have occurred in hospitals (6, 12). Ninety-five percent of soft-tissue RGM infections are caused by members of the M. chelonae complex (7), which comprises M. chelonae, M. abscessus, and M. immunogenum. However, the situation is complex for the clinical microbiologist who must rapidly and correctly identify isolates because there are reports of heterogeneity in M. abscessus isolates. Two M. abscessus groups (groups I and II) were reported on the basis of hsp65 PCR-restriction fragment length polymorphism (RFLP) (11) and sequence analysis (21) of hsp65. High heterogeneity of M. abscessus isolates was also shown by rpoB analysis (2). Meanwhile, new RGM species were reported: M. massiliense (4) and M. bolletii (1). These were very closely related to M. abscessus and M. chelonae but showed different susceptibility to clarithromycin, and their pathogenic potentials were shown by infections in immunocompetent and immunocompromised hosts (13,19).RGM infections are a...

Twenty two strains of Legionella species isolated from Jejudo, Korea were identified by comparing the rpoB (300 bp), dotA (360 bp), and mip (396 bp) gene sequence analysis. Furthermore, their genotypes were determined by sequence analysis of rpoB/dotA subgroup typing, pulse-field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) patterns. Of the 22 isolates, 21 strains were identified as L. pneumophila and 1 strain was close to L. erythra (>95% similarity of rpoB and mip). Most of the L. pneumophila strains (90%) belonged to P-I of rpoB/dotA subgroup typing, one strain of each P-III and P-IV. L. pneumophila isolates were further grouped into 4 and 6 different PFGE (P1 to P4) and RAPD (R1 to R6) patterns, respectively. On the basis of these genotypes, which may be useful for future epidemiological studies, existence of diverse L. pneumophilla population in Jejudo, Korea were observed.