Medias

Medium

Type

Why

TSA/ NA

·      General Purpose

·      Grows all MO except for fastidious

CBA

·      Enriched

·      Differential

·      Contains whole sheep’s blood

·      Observe hemolysis

CNA

·      Enriched

·      Differential

·      Selective

·      Contains blood

·      Observe hemolysis

·      Colistin and nalidixic acid -> inhbit Gram-neg

CHOC

·      Enriched

·      Contains lysed blood

è Release V factor and X factor

SDA

·      Selective

·      Low pH -> inhibits bacterial growth, promotes fungi growth

MSA

·      Differential

·      Selective

·      Mannitol and phenol -> pH indicator

·      7.5% inhibit most bacteria except staph. spp

MAC

·      Differential

·      Selective

·      Lactose fermenters turn pink, nonfermenters are colorless

·      Bile salts and crystal violet -> inhibit gram pos

HE

·      Differential

·      Selective

·      Sugar fermentation -> salmonella and shigella, H2S production

·      Bile salts inhibit gram pos