Basal (simple) media such as nutrient broth/agar support only non-fastidious organisms. Enriched media are basal media supplemented with extra growth factors — whole blood, lysed blood, serum, or egg — that fastidious organisms need but ordinary media cannot supply.
Examples: Blood agar (whole sheep blood — supports Streptococcus, Pneumococcus; also shows haemolysis pattern — beta/alpha/gamma), Chocolate agar (heated, lysed blood — releases NAD and haemin — supports Haemophilus influenzae, Neisseria), Loeffler’s serum slope (coagulated serum — Corynebacterium diphtheriae), Lowenstein-Jensen medium (egg-based — Mycobacterium tuberculosis).
