[Typing of pseudomonas aeruginosa by pyocine production. Experiments with a simplified method using four indicator strains (author's transl)].

A further differentiation of strains of Pseudomonas aeruginosa which have been isolated from clinical material is desirable because of the increasing frequency of hospital infections caused by this species. Only by such a procedure cross infections which require hygienic measures can be distinguished from autoinfections. Pyocine typing with a set of only four indicator strains was tried by repeated typing of 542 strains. Because of its simplicity and the small amount of material and working time required the method was found to be suitable for routine application. Reproducibility was satisfactory. The strains tested could be grouped into nine different pyocine types. Similar to the results of other typing procedures, 74 per cent of the strains belonged to three groups. The method is suitable for detection of sources of hospital infections caused by the more rare pyocine types. By a comparison of the antibiotic resistance patterns with pyocine types in strains which had been isolated from patients with chronic infections it was demonstrated that antibiotic resistance patterns could not be used as criteria for epidemiological investigations.