A Study of the Taxonomy of the Mycobacterium nonchromogenicum Complex and Report of Six Cases of Lung Infection Due to Mycobacterium nonchromogenicum

Abstract

In numerical classification, four species of the Mycobacterium nonchromogenicum complex, Mycobacterium nonchromogenicum, M. terrae, M. novum, and M. triviale, formed one cluster. These four species appeared to be reduced to one species, Mycobacterium nonchromogenicum. Furthermore, relationships between the species were numerically analyzed by using the hypothetical median organism pattern. The results showed that the M. nonchromogenicum complex can be divided into two subgroups: M. nonchromogenicum and the other three. These two subgroups were differentiated from each other by scores based on two or more positive reactions in the following three characteristics: resistance to bleomycin (5 pgjml); heat-stable acid phosphatase activity; nicotinamidase or pyrazinamidase activity or both activities. M. nonchromogenicum gave two or three positive reactions among these three, and M. terrae, M. novum, and M. triviale gave two or three negative reactions.Three cases of lung infection due to M. nonchromogenicum, as well as three other cases of probable lung infection due to M. nonchromogenicum, were observed in this study. Only one organism isolated from one doubtful case was M. terrae. Up to now, M. nonchromogenicum was considered a nonpathogen. It was shown, however, that this organism causes lung infection in humans. Wayne 1966 (36), M. novum Tsukamura 1966, and M. triviale Kubica et al 1970 (8) are closely related, slowly growing, nonphotochromogenic mycobacteria (16, 24). They form one cluster in numerical classification (24), and, based on this finding, were named the Mycobacterium nonchromogenicum complex (28). These organisms have been considered nonpathogenic, but recently there appeared several papers reporting infections due to these organisms (2,3,5,6,26). As will be stated below, the causative organisms were not adequately identified in these studies. The reason is the uncertain knowledge of the taxonomy of these organisms. There exists, at present, no reliable method of identification of these organsims. The 219 Mycobacterium nonchromogenicum Tsukamura 1965 (17), M. terrae

The division between fast- and slow-growing species corresponds to natural relationships among the mycobacteria

“…All three are nonpigmented slow growers. Numerical classification studies linked M. nonchromogenicum and M. terrae so closely that species distinction between them has been questioned (27,46). Based on the results of this study (98% similarity), the species distinction appears justified relative to other species of mycobacteria.…”

“…By these criteria, the genus was divided into the four Runyon groups: group I, slow-growing photochromogens; group II, slow-growing scotochromogens; group III, slow-growing nonphotochromogenic (nonpigmented) isolates; and group IV, the rapid growers. Numerical taxonomy offered additional criteria by which to define species but did not provide precise boundaries between some, such as between M. avium and M. intracellulare (27,31,35,(44)(45)(46)(47).…”

Survey of 150 strains belonging to the Mycobacterium terrae complex and description of Mycobacterium engbaekii sp. nov., Mycobacterium heraklionense sp. nov. and Mycobacterium longobardum sp. nov.

“…In our study, the isolations of M. nonchromogenicum and M. terrae were not as frequent as generally acknowledged. This brings up for discussion the widespread conviction that M. nonchromogenicum is the only member of the MTC potentially responsible for disease (Tsukamura et al, 1983).…”

Agents of newly recognized or infrequently encountered mycobacterial diseases

“…In 1983, Tsukamura and colleagues described six patients with pulmonary disease in whom M. nonchromogenicum was considered the possible etiologic agent (190). The mycobacteria isolated from all six of the patients were nonpigmented hydrolyzers of Tween 80 that exhibited high activity (>45 mm of foam) in the catalase test.…”