[Relationship between beta-lactamase activity of clinical strains of Pseudomonas pyocyanea and their resistance to penicillins].

The study of 50 clinical strains of Ps. aeruginosa revealed their high resistance to benzylpenicillin, ampicillin, oxacillin, streptomycin and kanamycin with a tendency to polyresistance. The same strains were highly sensitive to gentamycin and polymyxin. The strains produced constitutive beta-lactamase in small amounts. The enzyme synthesis in Ps. aeruginosa was induced by benzylpenicillin. Still high concentrations of it were required for the induction. The maximum induction of beta-lactamase synthesis was observed by the 6th hour of the inductor addition. The maximum induction level was observed 4 hours after addition of benzylpenicillin. The level of induction of beta-lactamase synthesis in the strains ranged within 5-93. A significant part of the enzyme was liberated from the cells during induction. Interaction between the induction level of beta-lactamase synthesis and resistance of Ps. aeruginosa to penicillins was found.