title: A new Mycobacterium species causing diffuse lepromatous leprosy.
abstract: Mycobacterium leprae causes leprosy. M leprae strains collected worldwide have been genetically clonal, which poorly explains the varying severity and clinical features of the disease. We discovered a new Mycobacterium species from 2 patients who died of diffuse lepromatous leprosy (DLL). The Mycobacterium was purified from heavily infected, freshly frozen autopsy liver tissue followed by DNA extraction in 1 case. Paraffin-embedded skin tissue was used for DNA extraction in another case. Six genes of the organism were amplified by polymerase chain reaction, sequenced on cloning or from amplicons, and analyzed. Significant genetic differences with M leprae were found, including a 2.1% divergence of the 16S ribosomal RNA (rRNA) gene, a highly conserved marker of bacterial evolution, and 6% to 14% mismatches among 5 less conserved genes. Phylogenetic analyses of the genes of 16S rRNA, rpoB, and hsp65 indicated that the 2 most related organisms evolved from a common ancestor that had branched from other mycobacteria. These results and the unique clinicopathologic features of DLL led us to propose Mycobacterium lepromatosis sp nov. This species may account for some of the clinical and geographic variability of leprosy. This finding may have implications for the research and diagnosis of leprosy.
authors.affiliation: Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Xiang Y
authors.initials: XY
authors.lastname: Han
authors.forename: Yiel-Hea
authors.initials: YH
authors.lastname: Seo
authors.forename: Kurt C
authors.initials: KC
authors.lastname: Sizer
authors.forename: Taylor
authors.initials: T
authors.lastname: Schoberle
authors.forename: Gregory S
authors.initials: GS
authors.lastname: May
authors.forename: John S
authors.initials: JS
authors.lastname: Spencer
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: R Geetha
authors.initials: RG
authors.lastname: Nair
mesh_terms: D000328:Adult; D001483:Base Sequence; D017809:Fatal Outcome; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D015440:Leprosy, Lepromatous / Q000382:microbiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D012336:RNA, Ribosomal, 16S / Q000032:analysis
chemical_list: D012336:RNA, Ribosomal, 16S