Glucose Cystine Blood Agar is an enriched microbiological medium designed for the isolation and cultivation of fastidious organisms, particularly Francisella tularensis. Each sterile plate contains approximately 20mL of nutrient rich agar supplemented with glucose, cystine, and defibrinated blood. Standard media are often insufficient for recovering this organism because it requires sulfhydryl containing compounds to grow. The addition of cystine fulfills this nutritional requirement while glucose provides a readily available energy source to promote cellular growth. The blood component contributes additional growth factors such as hemin and other nutrients required by fastidious microorganisms. On this medium, colonies of Francisella typically appear as small, smooth, grayish white colonies after extended incubation. The enriched formulation supports reliable isolation and recovery of demanding bacterial species in microbiological laboratories.