U01.03.004 Growth media

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Learning objective:

Certain pathogens require specific, enriched, or selective media to grow in the lab. Knowing these requirements is vital for proper diagnosis.

Organism(s)	Isolation Media	Key Contents / Function	Mnemonic/Context
Haemophilus influenzae	Chocolate Agar (Heated Blood)	Requires growth Factors V ( $NAD^{+}$ ) and X ( $hematin$ ). Heating lyses RBCs to release these factors.	H. influenzae craves chocolate that’s been enriched with Vitamin X ( $5 and 10$ ).
Neisseria gonorrhoeae $and$ N. meningitidis	Thayer-Martin Agar $(VPN)$	A selective medium containing Vancomycin (inhibits $G^{+}$ ), Polymyxin $or$ Colistin (inhibits $G^{-}$ except $Neisseria$ ), and Nystatin (inhibits fungi).	Very Typically Cultures $Neisseria$ (VPN $or$ VCN).
Bordetella pertussis (Whooping Cough)	Bordet-Gengou Agar $or$ Regan-Lowe Medium	Contains Potato Extract, Charcoal, $blood$ , $and antibiotic$ . Charcoal neutralizes toxins that inhibit growth.	Bordet for Bordetella.
Corynebacterium diphtheriae	Tellurite Agar $or$ Löffler Medium	Tellurite produces dark, gray/black colonies due to the reduction of the tellurite salt.	$Diphtheria$ tells you something ( $Tellurite$ ).
Mycobacterium tuberculosis	Löwenstein-Jensen (LJ) Medium, Middlebrook Medium, $or$ $rapid automated broth$	The LJ medium is an egg-based medium that can take weeks to show growth.	$Mycobacteria$ require $slow, low$ growth ( $L o ¨ wenstein-Jensen$ ).
Mycoplasma pneumoniae	Eaton Agar	Uniquely requires cholesterol for growth because it lacks a cell wall.	Eaton needs an egg (cholesterol is a key component of egg yolk).
Lactose-Fermenting Enterics $(e.g., E. coli, Klebsiella)$	MacConkey Agar	Fermentation produces acid, causing the colonies (and medium) to turn a pink or red color.	$text{The pink colonies on MacConkey Love Lactose.
E. coli	Eosin-Methylene Blue (EMB) Agar	Colonies exhibit a distinct green metallic sheen due to strong lactose fermentation.	E.coli Makes Bright Extra $shiny$ Green $colonies$ .
Legionella pneumophila	Buffered Charcoal Yeast Extract (BCYE) Agar	Requires cysteine and iron for growth. Often used for $Legionella$ .	Cysteine and Iron are key ingredients for Legionella to grow.
Fungi (General)	Sabouraud Agar	A medium with a low pH that inhibits the growth of most bacteria, allowing fungi to thrive.	“Sab’s a fun guy!”