A Novel Agar Medium to Detect Hydrogen Peroxide-Producing Bacteria Based on the Prussian Blue-Forming Reaction

The classic method for H2O2 detection involving Prussian blue formation was adapted to formulate a novel agar medium that makes possible in situ detection of H2O2 produced by bacteria. Using this medium, colonies of H2O2‐producing species including Streptococcus pyogenes were easily identified by the appearance of blue halos. The utility of the medium was further illustrated by its successful application to the isolation of H2O2‐producing mutants from a non‐H2O2‐producing stain of S. pyogenes.