[Trends in the spread of Boyd 4 dysentery and the characteristics of its clinical picture and of the biology of its causative agent].

The data on the proportion of S. boydii 4 in the general structure of the causative agents of dysentery, as well as in the intraspecific structure of S. boydii, in some areas of the USSR in 1977-1981 are presented. S. boydii strains 4, circulating in one of the areas where their proportion considerably increased in 1980-1981, corresponded to their taxonomic position in their biological properties, while forming a single biochemical variant according to the character of the fermentation of sorbitol, maltose and arabinose. These strains gave identical antibiotic sensitivity charts and showed pronounced multiple resistance to antibiotics, including ampicillin. The clinical features of the diseases caused by S. boydii 4 consisted in the sharply defined prodromal period and pronounced systemic toxicosis at the initial period of the disease, accompanied by the syndrome of moderate colitis localized mainly on the right side.