D/E Neutralizing broth is for the neutralizing and testing of antiseptics and disinfectants according to the procedure of Engley and Dey.

D/E Neutralizing broth is used for environmental sampling where neutralization of the chemical is important to determine its bactericidal or bacteriostatic activity. This medium will neutralize a broad spectrum of antiseptic and disinfectant chemicals, including quaternary ammonium compounds, phenolics, iodine and chlorine preparations, mecurials, formaldehyde and gluteraldehyde.

Casein peptone, yeast extract and dextrose are sources of nutrients required for the replication of microorganisms. Sodium thioglycollate neutralizes mercurials, sodium bisulfite neutralizes formaldehyde and gluteraldehyde and the sodium thiosulfate is able to neutralize iodine and chlorine. Lecithin neutralizes cationic surface-active agents, such as quaternary ammonium compounds; polysorbate 80, a non-ionic surface active agent, neutralizes phenolics.

Since the high concentration of lecithin renders the medium opaque, turbidity cannot be used to detect growth. Therefore, bromcresol purple and dextrose are added to the medium. Those organisms which ferment dextrose will turn the medium from purple to yellow. Growth of Pseudomonas species, which do not ferment dextrose, can be detected by the formation of a pellicle on the surface of the broth.