A Test for Penicillin Sensitivity and Resistance in Staphylococcus.

Abstract

SummaryThe results of penicillin sensitivity tests for staphylococci are influenced by the size of the inoculum on two accounts: (a) the presence in sensitive strains of a minority of resistant individuals originating by mutation; and (b) the occurrence of penicillinase-producing strains whose cells are individually sensitive to penicillin. A simple laboratory test is proposed for the detection and quantitative measurement of penicillin resistance in staphylococcus.