To Shigella sonnei phage typing.

The epidemiological significance of phage types changes in the course of years. In Czechoslovakia, in the years 1967-1971, the most frequent phage types were 2,6, 3, 30 and 65, and, in the Middle-Bohemian Region, 2,30, 6, 3 and 65. In the epidemiological years 1972-1973 the sequence of the most frequent S. sonnet phage types changed in the Middle-Bohemian region to: 65, 23, 6, 2 and 12. Some problems concerning the instability of phage types and the part of further auxiliary tests (biochemical differentiation according to Bojlen and drug sensitivity pattern) are discussed.