title: Molecular Identification of Rare Clinical Mycobacteria by Application of 16S-23S Spacer Region Sequencing.
abstract: OBJECTIVE
  In addition to several molecular methods and in particular 16S rDNA analysis, the application of a more discriminatory genetic marker, i.e., 16S-23S internal transcribed spacer gene sequence has had a great impact on identification and classification of mycobacteria. In the current study we aimed to apply this sequencing power to conclusive identification of some Iranian clinical strains of mycobacteria.
  
  
  METHODS
  The test strains consisted of nineteen mycobacterial isolates which were initially identified by the use of conventional phenotypic techniques and molecular methods and subjected to further definitive identification using the 16S-23S internal transcribed spacer gene sequencing.
  
  
  RESULTS
  Out of 19 studied strains, 7 isolates were found to be rapidly growing and 12 isolates as slowly growing mycobacteria. With the exception of one isolate, i.e., the isolate HNTM87, which yielded a distinct ITS sequence incomparable with all previously identified mycobacteria, the remaining isolates produced the sequences similar to the established mycobacteria and were clearly identified and differentiated from closely related taxa. A phylogenetic tree based on maximum parsimony analysis of 16S-23S internal transcribed spacer gene sequences constructed showing the relatedness of Iranian clinical isolates with the closely related type species of mycobacteria.
  
  
  CONCLUSIONS
  This study showed that the 16S-23S internal transcribed spacer gene of the genus Mycobacterium exhibits a high variation which is of value for discriminating closely related taxa and could be used independently or in combination with 16S rDNA sequencing to delineate the true identity of rare mycobacterial species.
authors.affiliation: Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Shojaei
authors.forename: Hashemi
authors.initials: H
authors.lastname: Abodolrazagh
authors.forename: Parvin
authors.initials: P
authors.lastname: Heidarieh
authors.forename: Fazel
authors.initials: F
authors.lastname: Pourahmad
authors.forename: Daei Naser
authors.initials: DN
authors.lastname: Daei Naser
keywords: Internal Transcribed Spacer; Mycobacterium; Sequence Analysis