A Pseudomonas pyocin typing method applicable to the clinical laboratory.

A new pyocin typing method for the identification of specific strains of Pseudomonas aeruginosa is described. The method involves a bilayer agar technique in which the pyocin produced by the organism diffuses from the top agar layer number 2 through a filter paper into the bottom agar layer number 1. The filter paper permits the removal of agar layer number 2 and exposes layer number 1 which is then streaked with the indicator strains. Pyocin typing of fifty clinical isolates using both the bi-layer method and the scrap-chloroform reference method of Gillies and Govan produced identical typing results. A total of 375 clinical isolates has been typed by this inexpensive and time-saving bi-layer agar method.