Epidemiological markers for Pseudomonas aeruginosa. VII. Nosocomial occurrence in urological ward. Comparison of two phage typing sets, pyocine typing, and serogrouping.

A comparison of two pyocine typing methods with serogrouping, and two phage typing sets has been made. In one instance, a contaminated bladder irrigation fluid of 0.05% silver nitrate solution caused a series of urinary tract infections. By all systems, fewer of the presentstrains were typable than usual. Among the phage typing sets the one developed by LINDBERG et al. typed only 66% whereas that selected by BERGAN typed 83%, both less than observed previously. The set of LINDBERG et al. also rendered longer pattern codes, and yielded more variable results with related strains. A set of pyocine indicator strains, selected among the strains to be typed, was more suitable than one developed elsewhere. Comparison of five different methods of epidemiological typing of Ps. aeruginosa indicated that phage typing alone is not entirely satisfactory for this species and should therefore always be combined with serogrouping.