Mycobacterium fragae sp nova, a non-chromogenic species isolated from human respiratory specimens

Three isolates of a slow-growing, non-chromogenic mycobacterium were grown from three sputum samples of a patient from the north-eastern Ceara state in Brazil. Identification at species level could not be obtained with PCR restriction analysis of the hsp65 gene. In order to characterize the isolates we carried out phenotypic and genotypic tests. We sequenced the nearly complete 16S rRNA gene and obtained partial sequences of the hsp65 (encoding the hypervariable region of the 65 kDa heat-shock protein) and rpoB (encoding the beta-subunit of RNA polymerase) genes. The three isolates turned out to be identical and most closely related to the species Mycobacterium celatum and Mycobacterium kyorinense. The results, however, showed significant differences between these species and the isolates studied, which led us to consider them members of a novel species for which we propose the name Mycobacterium fragae. The type strain is HF8705(T) (=Fiocruz-INCQS/CMRVS P4051(T)=DSM 45731(T)).