Numerical Classification of Rhodococcus (Formerly Gordona) Organisms Recently Isolated from Sputa of Patients: Description of Rhodococcus sputi Tsukamura sp. nov.

Abstract

A total of 116 strains of Rhodococcus (formerly Gordona) recently isolated from sputa of patients with pulmonary disease were submitted to numerical classification together with 61 reference strains belonging to the genera Rhodococcus, Nocardia and Mycobacterium. The numerical classification was carried out by 2 methods, 1 using 109 characters and another using 98 characters. Almost similar results were obtained by these 2 methods and the following clusters were distinguished: R. bronchialis (Synonym: G. bronchialis); R. sputi sp. nov.; R. rubropertinctus (synonym: G. rubropertincta); R. rhodochrous (synonym: G. rhodochroa); R. aurantiacus (synonym: G. aurantiaca); R. lentifragmentus (synonym: G. lentifragmenta); Nocardia rubra strains received from M. Ridell; N. asteroides; N. farcinica; Mycobacterium fortuitum. The 1st 7 clusters were combined into 1 large cluster, which was considered as the genus Rhodococcus (synonym: Gordona). Two (method I) or 4 (method II) new clusters could be observed among the cluster Rhodococcus. It was considered that the Rhodococcus organisms form a genus that contains a number of species. G. terrae and G. rosea were incorporated into the cluster of R. rubropertinctus (G. rubropertincta), and were considered to be reduced to varieties of the species R. rubropertinctus. The largest one of the new clusters was named R. sputi sp. nov. Tsukamura. Its definition is presented in this study. A proposal of changing the generic name from Gordona to Rhodococcus was made.