Abstract

Practical problems in the detection of penicillinase are discussed. A membrane technique for this purpose is described, with various modifications, suitable for screening large numbers of organisms and yet more sensitive than most methods.

A one-stage membrane technique is adequate for detecting hydrolysis of penicillin G but a two-stage technique is required to demonstrate hydrolysis of some other penicillins. A gradient adaptation can be used for quantitative purposes.

Staphylococci, coliforms, Proteus, and other organisms can be tested in this way for penicillinase formation; the method is also suitable for testing lysates, filtrates, and dialysates, provided independent provision is made for enzyme inducement.