16S approximately 23S rDNA internal transcribed spacer sequence analysis and its application in mycobacterial identification

OBJECTIVE: To study the applicability of the 16S approximately 23S rDNA internal transcribed spacer (ITS) sequences in mycobacterial identification. METHODS: The 16S approximately 23S rDNA ITS sequences of 22 mycobacterial species (30 reference strains and 16 clinical isolates) were determined by PCR-direct sequencing. The sequences determined by this study and those reported in Genbank were analysed by Clustal program (MegAlign Package [Windows Version 4.01]; DNASTAR, Madison, Wis). The percentage similarity of sequence pairs was calculated and a cluster analysis dendrogram was constructed by PHYLIP package. RESULTS: The 16S approximately 23S rDNA ITS sequences among mycobacterial species had highly polymorphism except that Mycobacterium tuberculosis complex (MTC) sequences were highly consistent. The similarity between sequence pairs was 30.4% to 86.5%. Mycobacterial species could be isolated by cluster analysis dendrogram. The results showed that sequence analysis of the 16S approximately 23S rDNA ITS can differentiate MTC from nontuberculous mycobacteria (NTM) and identify NTM at species level. CONCLUSION: 16S approximately 23S rDNA ITS sequences can be used as target genes in mycobacterial identification.