Mycobacterium confluentis sp. nov.

A new rapidly growing mycobacterium was isolated from human sputum. This organism grew at 22, 31, 37, and 41 degrees C and possessed catalase, acid phosphatase, acetamidase, urease, nicotinamidase, pyrazinamidase, and nitrate reductase activities. It did not produce nicotinic acid, hydrolyze Tween, or have benzamidase, isonicotinamidase, succinidamidase, and arylsulfatase activities. A mycolic acid analysis revealed a simple, unique pattern. The organism is susceptible to antituberculotic drugs. A comparative 16S rRNA sequence analysis placed this organism within the confines of the genus Mycobacterium, most closely related to the thermotolerant rapidly growing species. On the basis of the pattern of enzymatic activities and metabolic properties, as well as the unique 16S rRNA sequence, we propose that our single strain represents a new species, for which we propose the name Mycobacterium confluentis. The type strain is strain 1389/90; a culture of this strain has been deposited in the German Collection of Microorganisms and Cell Cultures as strain DSM 44017.