First Report of the Cooperative, Open-Ended Study of Slowly Growing Mycobacteria by the International Working Group on Mycobacterial Taxonomy

Abstract

An open-ended study has been initiated by the International Working Group on Mycobacterial Taxonomy to accommodate strains of slow growers that do not belong to well-established or throughly characterized species. Numerical taxonomic analysis of the data derived from the first series of cultures examined in this study has permitted preparation of expanded descriptions of Myco bacterium simiae and M. szulgai, and, to a lesser extent, M. asiaticum. The analysis also provides some support for revival of the name "M. shimoidei," which is presently without standing. Additional clusters have emerged which may represent new taxa; one of these includes a strain labeled "M. paraffinicum," a name which is also now without standing.Many commonly encountered species of slowly growing mycobacteria have been characterized in a series of cooperative taxonomic studies carried out by the International Working Group on Mycobacterial Taxonomy (IWGMT) (8,21,22). The rapid growers were characterized in two additional IWGMT studies (6, 12), as were members of the "rhodochrous" taxon (4) which is now recognized as Rhodococcus. In the original numerical taxonomic (NT) studies of the slow growers, some strains failed to aggregate with any of the major clusters and were too few in number to permit assignment to new taxa. To provide a mechanism for continuous introduction of unusual or rarely encountered strains into the mycobacterial taxonomic framework, the IWGMT has initiated a new effort, designated the Open-Ended Study of Slowly Growing Mycobacteria. Accession and detailed study of strains is an ongoing process; as new clusters emerge, their descriptions will be reported and, when appropriate, new species will be proposed. This is the first such report from the IWGMT open-ended study. MATERIALS AND METHODS Selection of strains.The data base for this study was derived from cultures meeting one of the following three criteria.(i) Reference marker strains. One culture was selected from a central position in each of the clusters that corresponded to named species in the three prior cooperative studies on slow growers (8,21,22). These 13 cultures, which are identified in the NT matrix (see Fig. l), were not redistributed for further examination; the data previously derived from them were transferred into the computer file reserved for the OpenEnded Study.(ii) Unclustered strains from the prior studies. These strains either appeared in an isolated position or were linked to one or two other strains in one or another of the previously reported studies. These cultures also were not redistributed, but the existing data were simply transferred into the new file.(iii) New accessions. Submission of strains for study was not limited to members of the IWGMT. Anyone wishing to submit a strain for consideration was required to forward it to one of the designated IWGMT transmitters

Numerical Classification of 280 Strains of Slowly Growing Mycobacteria

“…Kubica, Center for Disease Control, Atlanta, Georgia, U.S.A. (3)). e) This strain was reported as M. simiae by Wayne et al (51), but our identification was M. asiaticum. It is possible that mislabeling has occurred.…”

Fourth Report of the Cooperative, Open-Ended Study of Slowly Growing Mycobacteria by the International Working Group on Mycobacterial Taxonomy

“…The criteria for introducing new cultures into this study have been described previously (32,34 Editing and analysis of data. The criteria and editing programs for suppression of irrelevant, redundant, and incomplete data that were used in generating the NT matrices have been described previously (25,(32)(33)(34).…”

“…Subsequently, a cooperative open-ended study was initiated in which new strains of slowly growing mycobacteria were introduced on a continuing basis, and the data were analyzed at intervals (32)(33)(34). The purpose of this study of an expanding set of cultures was to characterize slowly growing mycobacterial strains that represented uncommonly encountered species that had not been represented in the first six studies, as well as to recognize clusters of previously unknown taxa.…”

“…asiaticum OES 90126 (from TMC 803 [ Editing and analysis of data. The criteria and editing programs for suppression of irrelevant, redundant, and incomplete data that were used in generating the NT matrices have been described previously (25,(32)(33)(34). Features were coded according to the RKC scheme of Rogosa et al (15).…”

Revival and emended description of ‘Mycobacterium paraffinicum’ Davis, Chase and Raymond 1956 as Mycobacterium paraffinicum sp. nov., nom. rev.

“…paraffinicum' was excluded because it was not clearly distinguishable from other species with the standard methods of analysis available at that time. Shortly thereafter, the IWGMT published on slowly growing mycobacteria with numerical taxonomic methods using 178 study characters (Wayne et al, 1981). They detected 10 clusters, and 'M.…”