日本, オランダおよびセイロン由来の人型結核菌のファージ感受性

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An investigation of the distribution of bacteriophage susceptibilities was carried out by using 99 strains of M. tuberculosis isolated from patients with pulmonary tuberculosis in Japan, 99 strains obtained from Netherland and 54 strains obtained from Ceylon. Phage susceptibilities were tested by spotting phage suspensions of routine test dilution (RTD) and 10×RTD on the lawn of mycobacteria. The name of the phages employed and the number of plaque forming unit being contained in RTD of each phage were shown in Table 1. All of the 11 mycobacteriophages (DS6A, AG1, BK1, BG1, GS4E, PH, Clark, Legendre, Sedge, DNA 1118, and D34) were employed in the case of Japanese and Netherland strains. The results obtained were as follows (Table 2): All strains except 3 were susceptible to DS6A and AG1. These 3 exceptional strains were resistant to all phages even by the spotting of 10×RTD. Number of strains susceptible to D34 was 4 in Japanese strains and 2 in Netherland strains. Susceptibility of Netherland strains to the remaining 8 phages were generally higher than that of Japanese strains (Table 3). For instance, the number of strains susceptible to all phages except D34 by RTD was 18 in Japanese strains and 34 in Netherland strains. Forty one Japanese strains and 11 Netherland strains were susceptible only to DS6A and AG1 by RTD. However, when 10×RTD phage suspensions were employed for spotting, most of them showed susceptibility to one or more phages in addition to DS6A and AG1. Especially, in the case of BK1 and BG1, marked differences in the number of strains lysed by 10×RTD and by RTD were noted (Table 3). In this case, a possibility of nonspecific growth inhibition by concentrated phage particles was excluded, since the number of plaque forming units being contained in one drop of 10×RTD ranged from about 102 to 5×104. Therefore, this phenomenon indicates that there are many strains which show intermediate susceptibility against these phages. Phage susceptibility patterns of the 54 Ceylon strains against DS6A, BK1, PH and D34 were shown in Table 4. In general, they were more susceptible to those phages than Japanese and Netherland strains: 87% were BK1 sensitive, 68% were PH sensitive, and 8% were D34 sensitive by the spotting of RTD. Distribution of bacteriophage types of these strains was compared using the scheme proposed by Bates and Fitzhugh. The distribution of Type A, B and C in Japan andin. Netherland was almost thesame. On the contrary, significant difference was observed between Japanese and Ceylon strains in the distribution of phage types (Table 5). Based on the results obtained, we thought that the following conditions should be taken into account in the selection of a typing phage set of M. tuberculosis: (1) select the phages which render a clear cut, easily detectablelysis; (2) select the phages which lyse similar number of strains by the use of both 10×RTD and RTD; (3) select the phages which do not lyse too manystrains: i.e. those which lyse approximately 10 to 20% of strains are preferable; (4) select the phages the lytic pattern of which overlap each other as little as possible; (5) select the phages so as to make the distribution of strains of certain phage types evenly and minimize the number of untypable strains. It was found that the mycobacteriophages employed in this study do not necessarily satisfy the above mentioned conditions, although it was possible tosubdivide M. tuberculosis strains to a certain extent.
日本結核病学会の論文

日本, オランダおよびセイロン由来の人型結核菌のファージ感受性

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