Epidemiological estimation of Pseudomonas aeruginosa strains isolated from different environments

117 P. aeruginosa strains have been isolated from hospital material (vascular ward), from ambulatory patients, from lake water samples and from animal environment. The serological characters of the above strains, their phage--typing patterns, their capability of producing ONPG hydrolase were compared in order to find out the strain with identical features responsible for nosocomial infections and also to find endemic infections. There were eleven polyagglutinable strains (isolated from sinks in the vascular ward) which agglutinated with two sera and one strain isolated from lake water. Apart from one exception there were no confirmations of the occurrence of the strains of identical features in different environments. Possible variability within the scope of somatic antigen and the phage typing of microorganism confirm the necessity to use several techniques to carry out studies of epidemiological significance.