Rapid identification of mycobacteria by gene amplification restriction analysis technique targeting 16S-23S ribosomal RNA internal transcribed spacer & flanking region.

BACKGROUND & OBJECTIVE: Conventional identification of a clinical isolate of mycobacteria primarily based on culture characteristics and biochemical tests needs several weeks and may remain inconclusive. This study was undertaken to develop a new rapid method to identify the mycobacterial isolates at species level by gene amplification restriction analysis using primers encoding 16S-23S rRNA internal transcribed spacer (ITS) region and flanking parts of the 16S as well as 23S rRNA gene.

METHODS

This system is based on the amplification of approximately 1.8 kb fragment encoding 16S-23S rRNA spacer region and flanking parts of the 16S as well as 23S rRNA gene. This assay was applied on 13 reference strains and 480 clinical isolates of mycobacteria to validate the technique. Restriction was carried out with three restriction endonucleases Hha I, Hinf I and Rsa I.

RESULTS

Distinct gene amplification restriction analysis patterns were obtained by restriction of amplicons with three distinct restriction endonucleases (Hha I, Hinf I and Rsa I) which could differentiate various mycobacterial species.

INTERPRETATION & CONCLUSION: Restriction patterns with the enzymes used in this study could clearly distinguish Mycobacterium tuberculosis complex from other non chromogenic clinically important species M. avium and M. intracellulare. Results indicated this assay to be a simple, rapid and reproducible method to identify clinically relevant mycobacteria.