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SummaryThe influence was studied of changes of the bacterial host strain on the course of inactivation of Staphylococcus phages A/5 and ϕ131 after u.v.-irradiation, gamma-irradiation and photodynamic inactivation by AO. Effectiveness of phage plating was alike on all the host strains used. An influence of the various bacterial host strains on the survival of inactivated phages was found for u.v.-irradiated phages only. The bacterial host strains could be divided into strain groups having a favourable effect on the inactivation course of u.v.-irradiated phages, i.e. increasing the number of surviving phage particles, and into bacterial strains which may further reduce the survival of inactivated phage particles. The possible presence of repair mechanism in Staphylococcus bacterial cells is discussed.

Pseudomonas-aeruginosa-Phagen wurden durch UV-, X-Strahlen und Afridinorange inaktiviert und die erzielte Wirkung auf die Differenzierung der DNS oder RNS enthaltenden Bacteriophagen untersucht. Es ergaben sich eine auffallend schwache Inaktivierung durch Akridinorange im Dunkelversuch und gegen Strahlenwirkung ausgesprochen sensible Phagen mit einfaseriger DNS und RNS.

Selected 22 phages of coagulase-negative staphylococci were tested against group-specific antisera for Staphylococcus aureus phages using a neutralization test. Fourteen of the tested phages were classified into the serological group B and one into the group F. All other phages were resistant to the antisera against S. aureus phages but cross-reacted with the antisera produced against themselves. Therefore they could be joined together into a new serological group of the staphylococcal phages.

Our phage-set, published in 1975 (6) was modified in that other staphylococcal hoststrains were found more suitable for the propagation. This new typing set of 15 phages should replace our old phage-sets. In comparing the phage-sets of Dr. Verhoef, Dr. Parisi and Dr. Blouse with our phages, the advantages of our new phage-set could be demonstrated. Lysogeny induction experiment with mitomycin C and UV-rays showed all staphylococcal host strains to be lysogenic. Conclusions of the studies performed were derived from and discussed.

Ps. aeruginosa strains--a frequement resuet of an irresponsible antibiotic therapy--represent a common agent of nosocomial infektions. At the same time, gravity of Pseudomonas diseases is also increasing. Lysogeny, bacteriocinogeny and frequent occurrence of autoplaques are the lytic manifestations of Pseudomonas aeruginosa strains which play a great role in the complexity of solving diagnostic, epidemiological end therapeutical problems connected with infections induced by these microbes. A survey is presented of the importance and utilization of the lytic properties of bacterial strains of Pseudomonas aeruginosa during the differentiation, epidemiological typing and further expansion of therapeutical possibilities in infections caused by Pseudomonas aeruginosa bacteria.