Special Culture Requirements

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