PPT 2 (SLIDE 52-102)

• Solid media – contains 2% agar

  • Colony morphology, pigmentation, hemolysis can be appreciated.
  • Eg: Nutrient agar, Blood agar
• Liquid media – no agar.

  • For inoculum preparation, Blood culture, for the isolation of pathogens from a mixture.
  • Eg: Nutrient broth
• Semi solid medium – 0.5% agar.

  • Eg: Motility medium
• Simple media / basal media

  • Eg: NB, NA
  • NB consists of peptone, meat extract, NaCl,
  • NB + 2% agar = Nutrient agar
• Complex media

  • Media other than basal media.
  • They have added ingredients.
  • Provide special nutrients
• Synthetic or defined media

  • Media prepared from pure chemical substances and its exact composition is known
• Enriched media

  • Substances like blood, serum, egg are added to the basal medium.
  • Eg. Blood agar, Chocolate agar
• Enrichment media

  • Liquid media used to isolate pathogens from a mixed culture.
  • Media is incorporated with inhibitory substances to suppress the unwanted organism.
  • Eg. Selenite F broth and Alkaline Peptone Water
• Selective media

  • The inhibitory substance is added to a solid media.
  • Eg. McConkey
• Indicator Media

  • These media contain an indicator which changes its colour when a bacterium grows in them.
  • Eg. Blood agar, Mac Conkey’s medium, Christensen’s urease medium
• Transport media

  • Media used for transporting the samples.
  • Eg. Stuarts medium, Buffered glycerol saline
• Anaerobic media

  • These media are used to grow anaerobic organisms.
  • Example: Robertson’s cooked meat medium, Thioglycolate medium.
• CULTURE METHODS

  • methods employed depend on the purpose for which they are intended.
• Culture Methods

  • Streak culture
  • Lawn culture
  • Stroke culture
  • Stab culture
  • Pour plate method
  • Liquid culture
  • Anaerobic culture methods
• STREAK CULTURE

  • Used for the isolation of bacteria in pure culture from clinical specimens.
• LAWN CULTURE

  • Provides a uniform surface growth of the bacterium
• Stroke culture

  • is made in tubes containing agar slope / slant.
• STAB CULTURE

  • Prepared by puncturing a suitable medium
• Liquid cultures

  • are inoculated by touching with a charged loop or by adding the inoculum with pipettes or syringes.