[Incidence of antibiotic resistance in Salmonella typhimurium strains isolated in different epidemic situations].

A total of 1800 S. typhimurium strains isolated in different regions of the USSR in 1968-1979 were studied. Of these strains, 68.6% were resistant to 6-8 antibiotics, 7.8% were resistant to 2-5 antibiotics, and 23.6% proved to be resistant to all antibiotics. The number of multiresistant strains sharply increased during the last 10 years. The strains isolated from different sources and in different epidemic situations considerably differed in their sensitivity to the action of antibiotics. The infective agents isolated from the hospital foci of salmonellosis were found to possess the maximum multiresistance. The study of the genetic nature of multiresistance showed that the multiresistance strains had a conjugative R-plasmid with resistance determinants CmTc, type Fin+, incompatibility group F1me. The phage typing of the strains with phages from the collection of the Tbilisi Research Institute for Vaccines and Sera revealed that these strains belonged to phagotype 2. The problems of the relationship between the biological properties of causative agents and the character of the epidemic process of the diseases caused by these agents are discussed.