Microbiological media

Submitted by amh10 on 14 March, 2007 - 20:36

What are the types of media?

  • Standard Media
  • Differential media (based on microbial phenotype, NOT SELECTIVE)
  • Selective media
  • Enrichment broths (supporting the growth of a particular pathogen)
  • Transport media - assuring the viability of all organisms

Transport Media:

  • AMIES (for GC)
  • STUART (for streps)

Enrichment Broths:

  • Robertsons (Cooked meat) broth - for anaerobes
  • Brain-Heart-Infusion broth
  • Universal broth
  • Selenite (for Salmonella spp)

Selective Media:

  • Bile Esculin agar:
    • Those organisms that hydrolyse esculin turn the media black: Enterococci, Strep. bovis, Listeria
    • Inhibitory to all "non-enteric" pathogens
  • Neomycin:
    • Inhibitory to all Gm (-) in wound swabs
  • TCBS (Thiosulphate-citrate-bile salts-sucrose):
    • Vibrio spp.
  • CLED
    • Bromothymol Blue
  • MaConkey:
    • NLF/LF
    • Bile salts
    • Enteric pathogens

Enteric Media:

  • Campylobacter
  • XLD (Xylose Lactose Deoxycholate)
    • Better than MaConkey
    • Unable to differentiate Proteus spp.
      • H2S producing
      • As do non-typhoidal salmonellae, even paratyphi (a little bit)
    • This is useful for initial speciation
    • Salmonellae and Shigellae can't ferment xylose
  • Shigella/Salmonella media

MRSA:

  • chromogenic
  • Oxacillin ->BORSA's-> false (+)
  • Cefoxatime mannitol salt agar
    • cefoxatime select MRSAs that escape salt.

AMH.

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