SUMMARYA total of 3217 strains of coagulase-negative staphylococci and micrococci were tested for susceptibility to a collection of phages isolated from coagulase-negative cocci; it was concluded that a useful typing scheme could be developed. Of the strains of Baird-Parker's biotype 1, 72 % were lysed by one or more phages, although rather a large proportion of strains are lysed by many phages to give a complex typing pattern.Normal persons commonly yield 10 or more distinguishable strains of coagulasenegative cocci in cultures from the nose and the skin.

One hundred and six strains of Klebsiella spp were examined for their ability to produce bacteriocine. Nine of these, together with one strain from the National Collection of Type Cultures, were selected and used to type Klebsiella strains from various sources. Strains were typed by testing their sensitivity to bacteriocines produced by the standard set of 10 strains. Eight hundred strains were tested and 77% of these were typable and could be divided into a relatively large number of groups, some of which occurred consistently more frequently than others.This simple method has been shown to have some value in epidemiological investigations.