Infection caused by an unusual isolate of non-tuberculosis mycobacteria in Iran

Abstract

Aims and objectives Sequence-based identification of non-tuberculosis mycobacteria (NTM) has become a method of choice in mycobacteriology laboratories and is accomplished by analysis of several targets, such as 16S rRNA, rpoB , hsp65 , sodA , etc. A group of pigmented, sl owl-growing mycobacteria were isolated from clinical samples of four unrelated patients with which were undefined at species level by means of phenotypic tests and hsp65-PRA method. The isolates were subjected to batteries of sequencing tests for identification. Methods From 2009 to 2014, a group of pigmented, slow-growing mycobacteria were isolated from respiratory tract specimens, soft tissue infection biopsies and abscesses of four unrelated patients across Iran. The isolates were not identified to species level by biochemical tests and hsp65-PRA. Then the isolates were subjected to identification by 16S rRNA, hsp65 and rpoB gene sequencing. Results Based on 16S rRNA sequencing, the isolates gave a closest match (99.8%) with Mycobacterium lentiflavum ATCC 51985 T of 99.4%, 99.2% and 99% with those of Mycobacterium simiae ATCC 25725 T , M. triplex ATCC 700071 T and Mycobacterium stomatepiae DSM 45059 T , respectively. The hsp65 gene sequence (356 bp) (GenBank accession: rpoB gene sequence (619 bp) (GenBank accession: FR695853 ) showed the highest similarities of 95%, 94.3% and 92.7% with M. triplex ATCC 700071 T , M. lentiflavum CIP 105465 T and Mycobacterium sherrisii Fl-94099, respectively. Conclusions The approaches used in the current study confirm the taxonomic status of this group of isolates as a novel Mycobacterium species. Further analysis is needed to fully characterize the isolates. The presence of unidentifiable NTM strains in the clinical setting emphasizes the need to use sequence analysis of genes for reliable identification.