Mycobacterium fortuiturn Subspecies acetamidolyticum, a New Subspecies of Mycobacterium fortuiturn

Abstract

Mycobacterium fortuitum subspecies acetamidolyticum is a new subspecies of M. fortuitum and has an intermediate growth rate. It is a nonphotochromogenic mycobacterium. It does not utilize glutamate but utilizes acetamide as a simultaneous nitrogen and carbon source. It is able to utilize acetate, malate, pyruvate, fumarate, glucose, fructose, and n-propanol as the sole sources of carbon in the presence of ammoniacal nitrogen, but does not utilize them in the presence of glutamate-nitrogen. It is easily differentiated from all rapidly growing mycobacteria by its inability to utilize glutamate as a simultaneous nitrogen and carbon source, and from all slowly growing mycobacteria by its capacity to utilize acetamide as a simultaneous nitrogen and carbon source. Its mycolic acid pattern is different from that of M. fortuitum. However, its deoxyribonucleic acid showed 94% relatedness with that of M. fortuitum. In view of the above findings, it has been designated as a new subspecies of M. fortuitum. The organism was isolated from sputum of a 56-year-old patient with lung disease and is considered to be a lung pathogen. The type strain is ATCC 35931 (NCH E11620).In the course of a search for mycobacteria in sputa of patients with lung disease, we found a new type of mycobacterium that was considered to be a lung pathogen. The organism belongs to the nonphotochromogenic mycobacteria with an intermediate growth rate and is differentiated by its phenetic characters and mycolic acid pattern from all named mycobacterial species, but showed a close relatedness with Mycobacterium fortuitum in the DNA relatedness study. MATERIALS AND METHODSNumerical analysis. Three isolates were obtained from sputum of a patient with lung disease and were compared with all named species except Mycobacterium leprae, M. lepraemurium, and M. paratuberculosis, which are auxotrophic mycobacteria. For comparison with rapidly growing mycobacteria, 104 characters were used (11).

Numerical Classification of Rapidly Growing Nonphotochromogenic Mycobacteria

“…It is suggested that this organism is not a simple mutant of M. fortuitum but is a definitively different organism. The fact that this organism has a unique mycolic acid pattern supports this concept (31).…”

“…acetamidolyticum was clearly distinguished from all the other species by the present study. In a previous study, this taxon was considered to be distinct by phenetic analysis and mycolic acid analysis (31). However, it was not differentiated from M. fortuitum by DNA hybridization study and thus it was included in the species of M. fortuitum (31).…”

“…However, in fact, there are some instances of a discrepancy between the two studies, as seen in the case of M. fortuitum subsp. acetamidolyticum (31).…”

“…In a previous study, this taxon was considered to be distinct by phenetic analysis and mycolic acid analysis (31). However, it was not differentiated from M. fortuitum by DNA hybridization study and thus it was included in the species of M. fortuitum (31). This organism has the unique characteristic that it is unable to utilize glutamate as nitrogen source or as a simultaneous nitrogen and carbon source in contrast to the facts that all other mycobacteria can utilize glutamate as a nitrogen source and all rapidly growing mycobacteria can utilize glutamate as a simultaneous nitrogen and carbon source.…”

Multiple-Genome Comparison Reveals New Loci for Mycobacterium Species Identification

“…acetamidolyticum from M. fortuitum subsp. fortuitum strains which differ in traditional clinical diagnoses, including mycolic acid patterns (50), nor can it differentiate species within the M. tuberculosis complex (MTBC) or the M. avium complex (51). Also, the first 500 bp of the 16S rRNA gene is identical between pairs of M. marinum-M. ulcerans (51), M. abscessus-M. chelonae, and M. vaccae-M. vanbaalenii (11) isolates.…”