Heterogeneity of Iranian clinical isolates of Mycobacterium fortuitum

The increase of infections caused by nontuberculous mycobacteria (NTM) is receiving increasing attention worldwide. Mycobacterium fortuitum is encountered with increasing frequency in clinical laboratories of Iran. Sequence variation of 48 M. fortuitum clinical isolates, were investigated by sequence analysis of the 16S-23S Internal Transcribed Spacer. Twelve different sequence types (sequevar) were identified by sequence analysis of ITS region. Seven previously described sequevar including MfoA, MfoB, MfoC, MfoD, MfoE, MfoF and MfoG identified. Five novel sequevar namely MfoH, MfoI, MfoJ, MfoK and MfoL that were distinctly different from the previously described sequevar were detected among different clinical strains of M. fortuitum, from Iran. This study showed that the ITS region possesses high discriminatory power between the clinical isolates up to the clonal level. The results also suggest the possibility of the existence of predominant clone of M. fortuitum in affected patients in Iran. The data also point to the conclusion that a large variety of M. fortuitum clone can produce disease although certain clones seem to be predominant.