Bile Esculin Agar (BEA) is a selective and differential medium used for the isolation and presumptive identification of Group D Streptococci and Enterococci. Each sterile 100 × 15 mm plate contains 20 mL of nutrient agar formulated with beef extract, peptones, bile salts (oxgall), esculin, and ferric citrate. Bile salts inhibit most gram positive bacteria except enterococci and Group D streptococci, enabling selective growth. Organisms capable of hydrolyzing esculin produce esculetin, which reacts with ferric citrate to form a dark brown to black complex within the agar. This visible blackening around colonies provides a clear diagnostic indicator. The medium is widely used in clinical and food microbiology laboratories for rapid screening and differentiation of Enterococcus species and related organisms.