Quick Review Cards for Medical Laboratory Science

Types of Media Clinical Microbiology Review 148

TYPE EXPLANATION EXAMPLES

Supportive

Enrichment

Selective

Differential

Note: Media may be of more than 1 type, e.g., selective & differential.

Nutrient agar, trypticase soy agar

Sheep blood agar, chocolate agar, brain-heart infusion,

buffered charcoal-yeast extract agar

Columbia colistin–nalidixic acid (CNA) agar, eosin

methylene blue (EMB), MacConkey, Hektoen enteric

(HE), xylose lysine deoxycholate (XLD), Thayer-Martin

EMB, MacConkey, HE, XLD

Supports growth of most nonfastidious bacteria

Contains added growth factors, e.g., blood, vitamins, yeast

extract

Contains additives such as dyes, bile salts, alcohols, acids,

or antibiotics to inhibit growth of certain bacteria (e.g.,

gram pos)

Formulated to provide distinct colonial appearances based

on certain biochemical rxn (e.g., lactose fermentation,

hydrogen sulfide [H 2 S] production)