The epidemic spread of Salmonella typhimurium phage type 10 in Canada (1970-1979)

The frequency of Salmonella typhimurium phage type 10 across Canada was monitored during the period 1970-1979. Phage type 10 isolations increased from 1.2% in 1970 to 68.8% in 1979 among isolates from human sources and from 1.5 to 30.6% in isolates from nonhuman sources. Examination of food-poisoning outbreaks and a study of the animal-host associations of phage type 10 revealed that contaminated poultry products appear to be the most common sources of human infections. The majority (89.3%) of S. typhimurium phage type 10 strains were sensitive to antibiotics. Of the resistant strains, 73.3% were resistant to single antibiotics and 26.7% were multiresistant. Thirty-three different patterns of antibiotic resistance were observed. A number of the resistance determinants were transferable by conjugation and the R plasmids were found to belong to the incompatibility groups HI1, FII, N, I alpha, and C.