In the period from 1992 to 2001, 303 cases of nocardioses were diagnosed in Japan, with the corresponding etiological agents isolated and characterized. Taxonomic analyses of these 303 strains showed that most nocardial infections were caused by members of the Nocardia asteroides group (72.3%). Speciation showed that 72 strains were N. asteroides, 31 strains were N. cyriacigeorgica, 2 strains were N. beijingensis, 81 strains were N. farcinica, and 33 strains were N. nova. Sixty-six strains of N. brasiliensis were the next most prevalent species of the total Nocardia isolates, followed by 14 strains of N. otitidiscaviarum. Infections by N. transvalensis (3 strains) and N. pseudobrasiliensis (1 strain) were also confirmed. The infections due to N. transvalensis, N. cyriacigeorgica, and N. beijingensis were the first reported in Japan. The most common factor that predisposed individuals to nocardial infection in Japan was therapy by immunosuppressive agents (22.4%), including SLE therapy (3.6%), followed by cancer (6.6%), diabetes (3.6%) and AIDS (2.0%). Nocardial infections occurred more commonly in the elderly, with most of the patients between the ages of 61 and 80 years of age. No significant difference regarding infectivity levels between the sexes was observed.

Three strains of Eubacterium aerofaciens, JCM 10188T, JCM 7790 and JCM 7791, and 178 freshly isolated strains of the Eubacterium aerofaciens group from human faeces were characterized by biochemical tests, cell wall peptidoglycan type and 165 rRNA analysis. The Eubacterium aerofaciens group was divided into four groups by fermentation patterns of sucrose and cellobiose, and were further divided into 16 sub-groups by fermentation patterns of aesculin, salicin and amygdalin. All of the strains of the Eubacterium aerofaciens group were shown to be phylogenetically distantly related to Eubacterium limosum, which is the type species of genus Eubacterium. Eubacterium aerofaciens was shown to have a specific phylogenetic association with Coriobacterium glomerans. All the strains belonging to Eubacterium aerofaciens resembled Coriobacterium glomerans in possessing a high G+C content (60 mol%). Cell wall analysis, however, revealed the presence of different A4P (L-Ala)-D-GIu-L-Orn-L-Asp peptidoglycan types. Based on a 165 rRNA sequence divergence of greater than 9 % with Coriobacterium glomerans and the presence of a unique peptidoglycan type, a new genus, Collinsella, is proposed for Eubacterium aerofaciens, with one species, Collinsella aerofaciens. The type strain of Collinsella aerofaciens is JCM 101 88T.

Phylogenetic evidence for the transfer ofEubacterium lentum has unique phenotypic characters within the genus Eubacterium. The 165 rRNA sequence of Eubaderium lentum was determined and its phylogenetic position was defined. This micro-organism is a member of the genus Eubacterium but it is not closely related to Eubacterium limosum, the type species of the genus Eubacterium, and is nearer to Collinsella aerofaciens and Coriobacterium glomerans. A PCR-based identification system using species-specif ic primers designed on the basis of DNA sequences encoding the 16s rRNA of strains of Eubacterium lentum, Collinsella aerofaciens and Coriobacterium glomerans is described. A species-specif ic primer set can distinguish Eubacterium lentum from Eubacterium limosum or close I y re I a ted species i ncl ud i ng Collinsella aero faciens, Coriobact erium glomerans and Atopobium species. This species-specif i c PCR method can be used to identify Eubacterium lentum-like species isolated from human faeces. On the basis of the 16s rRNA sequence divergence from Collinsella aerofaciens and Coriobacterium glomerans and the presence of unique phenotypic characters, a new genus, Eggerthella gen. nov., is proposed for Eubacterium lentum, with one species, Eggerthella lenta comb. nov. The type strain of Eggerthella lenta is JCM 997gT.

Six strains of Eubacterium-like strains from human faeces were characterized by biochemical tests and analysis of cell wall peptidoglycan type and 16S rRNA. They were members of the Clostridium subphylum and have a specific phylogenetic association with Lactobacillus catenaformis and Lactobacillus vitulinus. These organisms resembled L. vitulinus in possessing the same A1γ type of murein, but they showed different fermentation end-products. On the basis of a 16S rDNA sequence divergence of greater than 8 % from L. vitulinus as well as phenotypic characteristics, a new genus, Catenibacterium, with one species (Catenibacterium mitsuokai), is proposed for six strains. The type strain of C. mitsuokai is JCM 10609 T .

Three isolated strains from human feces were characterized by biochemical tests and 16S rDNA analysis. Phylogenetic analysis revealed that these isolated strains were members of the Clostridium subphylum of Gram-positive bacteria. The phenotypic characters resembled those of the genus Eubacterium, but these strains were shown to be phylogenetically distant from the type species of the genus, Eubacterium limosum. The strains showed a specific phylogenetic association with Holdemania filiformis and Erysipelothrix rhusiopathiae. Based on a 16S rDNA sequence divergence of greater than 12 % with H . filiformis and E. rhusiopathiae, a new genus, Solobacterium, is proposed for three strains, with one species, Solobacterium moorei. The type strain of Solobacterium moorei is JCM 10645T.