Cytochemical Mechanisms of Penicillin Action

Abstract

The present work is a continuation of our studies of the changes induced by penicillin and certain other diffusible substances in susceptible test organisms. Proper application of suitable staining techniques to assay plates clearly demonstrates inhibition zones around "penicylinders" containing bacteriostatic concentrations of penicillin within 2 to 3 hours after the antibiotic has begun to diffuse through a test plate, although no measurable zones are evident on untreated plates until several hours later. Among the reagents that have been useful for revealing zones of inhibited bacterial activity are appropriate redox indicators, notable among which is triphenyl-tetrazolium chloride," and certain dyes that have been recommended for the detection of nucleic acid. A summary