Used in microbiology laboratories to isolate and differentiate gram-negative bacteria, especially coliforms and fecal coliforms from water, food, and clinical samples. Supports the growth of enteric bacteria while inhibiting gram-positive organisms due to the presence of methylene blue. Eosin and methylene blue dyes react with certain bacteria to produce distinctive colony colors—E. coli typically shows a greenish metallic sheen, aiding in its identification. Commonly used in water quality testing to detect fecal contamination. Also helpful in identifying lactose-fermenting versus non-lactose-fermenting enteric bacteria based on colony appearance.