Correlation between staphylococcal serotypes with 263-1 factor and phage group 1.

Strains of staphylococci prevalent in hospitals have been characterized by antibiotic-sensitivity patterns, phage type, serotype, and other criteria. Recently, T. Hofstad and P. Oeding (Acta Pathol. Microbiol. Scand. Suppl. 154, p. 311, 1962) reported on the development of a factor serum, 263-1, which agglutinated phage group I strains predominantly. This note is a corroboration of the findings of Hofstad (Acta Pathol. Microbiol. Scand. 61:558, 1964). plates, and adsorption was carried out sequentially. The cells, usually from four large petri dishes (150 mm in diameter), were used to adsorb 10 ml of serum diluted 1:10 with 0.85% saline. Cultures were typed with factors a, b, cp, cl, h, i, k, m, and n, as well as 263-1, according to the methods reported by Cohen and Smith. The results of testing 620 strains of staphylococci with serum 263-1 are shown in Table 1. There were 172 cultures which agglutinated in