PYOCINE-TYPING OF HOSPITAL STRAINS OF PSEUDOMONAS PYOCYANEA.

A method of typing Pseudomonas pyocyanea is described which makes use of the property of bacteriocine production. The method was applied in an epidemiological study of Ps. pyocyanea infection in a general hospital. It was found that the majority of strains believed on epidemiological grounds to be of common origin were allotted to the same pyocine type. In the course of this study, Ps. pyocyanea was isolated from 219 patients; 474 strains from 149 of these were typed. There was evidence of cross-infection among patients in a urogenital surgical ward, but in other parts of the hospital there appeared to be little cross-infection. A number of individual instances of auto-infection, possibly arising from the bowel flora, were seen.