Correlation of phage type, biotype and source in strains of Salmonella typhimurium

A series of 2092 cultures of Salmonella typhimurium isolated from human, animal and other sources in 57 countries were differentiated into 204 phage types and 19 primary and 147 full biotypes. Different biotypes belonged to the same phage type and different phage types to the same biotype, so the combination of typing methods differentiated strains more finely than either method alone: 574 different `phage type/biotypes'' were distinguished in 1937 cultures belonging to the 204 recognized phage types.