[Increasing the effectiveness of the method of Staphylococcus phage-typing]

Eight nutrient media used for St. aureus phage-typing were assessed in parallel experiments. 22 test strains of St. aureus with previously known bacteriophage formulas and 44 strains isolated from different sources during food poisonings were subjected to typing. Bacteriophages were employed in the test dose (TD) and in 10 TD. Marked relationship was established between the degree of lytic reactions of bacteriophages used in the TD and the type of solid nutrient media. The best results of phage-typing as regards the strength of lysis were obtained on agar for Brucella isolation (erythritol agar) with all bacteriophages applied in the TD. The results appeared similar to those obtained with Hottinger's medium. In order to unify the method of Staphylococcus phage-typing, it is suggested that dry erythritol agar manufactured by the Dagestan Research Institute for Nutrient Media should be used as a solid medium. In addition, two procedures for St. aureus cultivation before phage-typing are offered, raising the percentage of cultures lysed by bacteriophages.