تشخيص٣

• Identification of bacteria


  1. Primary isolation

  2. Colony purification
• Identification of bacteria based on

  • Colony morphology
  • Gram's stain (or specialized stains)
  • Catalase reaction
  • Oxidase reaction
  • Growth on MacConkey agar
  • Oxidation-fermentation test
  • Motility test
  • Secondary identification tests
• Colony


  Macroscopically visible collection of millions of bacteria originating from a single bacterial cell
• Types of culture media based on consistency

  • Solid medium
  • Liquid medium
  • Semi solid medium
• Types of culture media based on constituents/ingredients

  • Simple medium
  • Complex medium
  • Synthetic or defined medium
  • Special media
• Types of culture media based on oxygen requirement

  • Aerobic media
  • Anaerobic media
• Simple media


  • Nutrient agar (NA)
  • Nutrient broth (NB)
• Enriched media, Indicator media

  • Blood agar (BA)
• Selective, Indicator and Differential media


  • Mac Conkey's medium
• Media for biochemical reactions

  • TSI
  • Indole tests
• Culture methods


  1. Streak culture

  2. Lawn culture

  3. Stroke culture

  4. Stab culture

  5. Pour plate method

  6. Liquid culture
• Anaerobic bacterial culture methods

  1. Incubate the cultures in a vacuum desiccator

  2. Candle jar

  3. CO2 bags

  4. McIntosh – Fildes' anaerobic jar

  5. CO2 incubator
• Biochemical tests


  • Oxidase test
  • Triple sugar iron agar (TSI)
  • Indole test
  • Citrate utilization
  • Urease test
• Biochemical tests provide additional information for the identification of the bacterium