questions 3

Special Culture Requirements

Topic updated on 11/19/16 3:58am

  • 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


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