Special Culture Requirements - Microbiology

Overview

Haemophilus influenzae
- chocolate agar
  - factor V (NAD⁺)
  - factor X (hematin, a precursor of hemin)
Neisseria gonorrhoeae
- Thayer-Martin (VPN) media
- selects for N. gonorrhoeae growth only
  - vancomycin
    - inhibits gram-positive organisms
  - polymyxin
    - inhibits gram-negative organisms
  - nystatin
    - inhibits fungi
Mycoplasma
- cholesterol
Salt
- Staphylococcus aureus can grow in high levels of salt
- Vibrio spp. requires NaCl to grow and grows in 6.5% NaCl
- Enterococci (group D streptococci) grows in 6.5% NaCl
  - differentiates from non-enterococcal group D strepococci (S. bovis)
Bile
- group D streptococci can grow in bile (both Streptococcus bovis and Enterococci)
- Klebsiella can grow in bile
Mycobacterium tuberculosis
- Löwenstein-Jensen agar
Mycoplasma pneumoniae
- Eaton's agar
- Mycoplasma must be given a long time to grow
Bordetella pertussis
- collect culture with calcium alginate swab
- Regan-Lowe medium
- Bordet-Gengou (potato) agar
  - "BORDETella"
Corynebacterium diphtheriae
- Cysteine-tellurite agar
  - forms metachromatic granules detected with methylene blue stain
- Löffler's media
Fungi
- Sabouraud's agar
  - especially used for dermatophytes
- fungi causing systemic infections must be given a long time to grow!
  - e.g. Blastomyces, Histoplasma, Coccidioides
Legionella
- charcoal yeast extract agar with cysteine and iron
Cysteine required
- Francisella
- Brucella
- Legionella
- Pasteurella
Lactose-fermenting enterics
- MacConkey's agar
  - pink colonies
  - due to acid production by fermentation
  - contains bile to inhibit growth of unwanted organisms
- EMB agar (eosin-methylene blue)
  - also used to differentiate lactose-fermenting bacteria
  - Escherichia coli appears with metallic green sheen