Abstract

Commercially available O antisera have been compared with a standard pyocine typing method in the investigation of 156 strains of Pseudomonas aeruginosa. A third of the strains belonged to serotypes 3 or 6 and 42·3% to pyocine type 1. Good differentiation of strains belonging to the predominant serotypes was achieved by pyocine typing. Although routine use of both methods provides a more complete discrimination between strains, the simplicity of serotyping renders it more suitable for use in the smaller laboratory, where only one method may be feasible. If desired, pyocine typing can be reserved for the strains which cannot be distinguished serologically.