The use of bacteriophages in typing Salmonella cultures.

The methods of Salmonela diagnosis and typing are well standardised and essentially the same all over the world. The biochemical differentiation of a strain is followed by the serological analysis of the antigenic fraction according to the Kauffmann-White schema. Agglutinating sera for 0, Vi, and H antigens, as well as absorbed sera for single factor determination, are used, but at present no bacteriophages are commonly applied in the routine typing techniques. Phages are employed, however, for special purposes, such as the differentiation of Vi types in Salmonella typhosa or in some SalmoneUa paratyphi B cultures. Cherry et al. (1953) investigated the relation of S. paratyphi B to a number of specific phages. Similar studies were made by Lilleengen (1948, 1950) with Salmonela typhitnurium, Salmonella dublin, and Salmonella enteritidis and by Smith (1950) with Salmonella tompson. Atkinson and co-workers (1952, 1953) in Australia demonstrated various phages adsorbed by Salmonella waycross, Salmonella adelaide, and Salmonella bismorbificans. Cherry et al. (1954) have reported the successful adaptation of the 0-1 phage of Felix and Callow to the identification and screening of the genus Salmonella. Phages for H antigens in Salmonellae have been described by various investigators, particularly by Rakieten and Bornstein (1941). There are, however, no reports to our knowledge which make use of bacteriophage as a tool for routine typing of Salmonellae. At the New York Salmonella Center an investigation was undertaken with the intention of developing phages suitable for diagnostic purposes and comparing the efficiency of this method with the accepted serological one. The increasng number of Salmonella types listed in the Kauffmann-White schema made it imperative to select the bacteriological material from the most prevalent groups. The majority of cultures handled in these laboratories belongs to the B, C1, C2, D, and E groups. Less than 1 per cent of 1,000 Salmonella strains emined between May, 1953, and April, 1954, was found to belong to groups other than these. Therefore only phages for these principal groups were prepared.