Identification of clinical isolates of Mycobacterium spp. by sequence analysis of the 16S ribosomal RNA gene - Experience from a clinical laboratory

Twenty-one mycobacterial type strains and 334 clinical isolates of mycobact eria were identified by standardized sequence analysis using part of the ge ne encoding 16S rRNA. Apart from two clinical isolates, the resulting seque nces corresponded to previously published sequences. The results of the mol ecular determinations of the type strains completely overlapped the identit ies obtained using conventional techniques (cultural characteristics, bioch emical tests, commercial DNA probes, and gas chromatographic lipid profiles ). Of 323 isolates conventionally identified as slow-growing mycobacteria, 318 (98.5%) were identified to the same species or group level by 16S rDNA sequence analysis, while 6 of the 11 strains of rapid growers obtained a co rresponding identity with the two approaches. The sequencing protocol combi ned with a few cultural characteristics (i.e. growth rate, pigmentation and susceptibility testing) offers a rapid, reliable and usually definite iden tification of mycobacterial isolates.