A collaborative investigation of phages for typing bovine staphylococci.

Seventeen collaborators tested a total of 6 999 cultures. The results were used to assess the usefulness of each phage for typing bovine staphylococci and to classify the phages into lytic groups and the cultures into phage groups. Some marked differences in the distribution of phage patterns from country to country were found. Evidence concerning the stability of the phage patterns is presented. On the basis of the results, a set of phages that would be generally useful for typing bovine staphylococci was selected. This set was established as the international basic set of phages for typing bovine staphylococci by the International Subcommittee on the Phage Typing of Staphylococci.