Dichloran Rose-Bengal Chloramphenicol (DRBC) Agar Dichloran Rose Bengal Chloramphenicol Agar is based on the formulation described by King et al. It is a selective medium for the isolation and enumeration of yeasts and mould that are of significance in food spoilage. The medium is a modification to Rose Bengal Chloramphenicol Agar and is recommended by the International Standard ISO 21527:2008 part 1.