Observations on the Mechanism of Action of Penicillin. ∗

Abstract

Summary

Penicillin acts either as a bacteriostatic or bactericidal agent depending on the experimental conditions. The number of organisms decreases at a constant rate until 99% of the organisms have been destroyed. The rate of killing varies with different organisms. The action of penicillin on hemolytic streptococci is not accompanied by lysis of the organisms. No detectable amount of penicillin is destroyed or absorbed from solution by the organisms. It appears to be effective only when active multiplication takes place.