昭和25年, 26年及び27年北海道において分離された赤痢菌の菌型について

Shigella strains, which were isolated from dysentery patients and carriers in Hokkaido from 1950 to 1952, were identified as to types and subtypes. The results are summarized in the table below. In 1950 the most frequently isolated subtype was Shigella flexneri 3 a, followed by Sh. flex. 2 a and Sh. flex. 1 b in order. (Other types or subtypes are omitted as the number of strains are negligible). In 1951 and 1952, however, the most frequent subtype was Sh. flex. 2 a, followed by Sh. flex. 3 a, Sh. flex. 1 b and others in order. The statistical analysis revealed that Sh. flexneri 2 a increased in rate of frequency in 1951 and 1952 as compared with in 1950. Beside the above, it was found that the ratio of number of indole positive strains to that of indol negative strains within one and the same subtype changed with the year. In both Sh. flex. 2 a and Sh. flex. 1 b, indole positive strains increased in rate of frequency in 1952 as co-mpared with in 1950