Studies on penicillinase produced by a strain of Staphylococcus aureus

Some aspects of the induction of penicillinase formation in penicillin-resistant strains of staphylococci have been studied, particularly with respect to methicillin and benzylpenicillin. The greater effectiveness of methicillin, in this respect, is shown to be due largely to greater stability towards penicillinase. A method of preparing cell-free penicillinase is described, and some properties of this and the penicillinase of whole cells, reported. The Michaelis constants for a number of penicillins are given and their significance with regard to the effectiveness of the penicillin against penicillinase-producing staphylococci is discussed. The inactivation of staphylococcal penicillinase by high concentrations of substrate is described.