Vi抗原およびSalmonella菌株と共通のO抗原を有するBacterium typhi-flavumの1菌株

A yellow pigment producing organism of Gram-negative, flagellated bacillus was isolated from the blood of a feverous patient. The serum of the patient taken on the fifth disease day showed comparatively high titer (1: 640) in the agglutination test with this organism. On isolation, this organism had possessed Vi-antigen, since the living and heated bacilli or this strain had been agglutinated by anti-Vi sera to full titer, but not by anti-S. typhi 0901 serum. However, on successive subculture on agar, the Vi-antigen was lost in 2 months after isolation and the organism showed reaction with anti-S. typhi 0901 serum. Contray to the first apperance that the organism seemed to be a strain of S. typhi, it was identified as Bact. typhiflavum by its culturai and biochemical properties (Cf. Cruickshank: J. Hyg., 1935, 35, 354). It formed so-called “Symplasmata” discribed by Kathe (1933) on agar slant, especially in the part of condensed water.As to the serological relationship between Bact. typhi-flavum and Salmonella groups, no satisfactory description could be found in the literature. Therefore, an attempt was made to investigate it using the isolated organism and more than 30 different Salmonella serotypes. After the many cross-absorption tests, it was found that this strain of Bact. typhi-flavum possessed such 0-antigens as Salmonella 0122, 13, and 34. Besides, it contained some partial 0-antigens common to such Salmonella serotypes as S. newington, S. albany, S. hoi-sham, S. minnesota and S. tel-aviv, respectively. By slide agglutination tests, the organism showed no reaction with any anti-H standard serum of Salmonella.On the cultivation in bile containg broth, the organism grew easily a variant strain producing no yellow pigment. Serologically this strain was identical to the original strain, but different in the fact that it did not ferment maltose and formed no symplasmata.Although the pathogenicity of the organism for mice was so weak, that on M. L. D. was about 7mg of culture by intraperitoneal inoculation, the present study, together with the literature survey, suggests that Bact. typhi-flavum would cause mild typhoid fever in man depending on conditions.