Let’s discuss about Blood Culture


An artificial food for the cultivation of microorganisms in laboratory.

★ Types :

  1. On the Basis of Consistency:

Solid media (Nutrient agar , Blood agar, Chocolate agar)

Semisolid media (Soft Agar Media)

Liquid media (Peptone water, Bile broth, Sugar broth)

  1. On the basis of oxygen requirement :



  1. On the basis of Chemical Composition :

Simple media

Special media :

  • Enriched media– Blood agar medium.
  • Enrichment medium – Tryptic soya broth.
  • Selective media– Mac Conkey’s agar , Blood tellurite agar.
  • Indicator media -Blood agar.
  • Transport media – Stuart media.
  • Storage media – Egg saline medium.

★ Today we will discuss about Blood Enriched media’s :

Blood Agar :

Media Identifying point :

  • Red colour , Solid enriched Media

Composition :

  • Nutrient Agar + 5-10% Sheep Blood

Indication of Blood Culture :

  1. Enteric fever
  2. Septicaemia
  3. Bacteremia
  4. Meningitis
  5. Pyrexia Of Unknown Origin
  6. Bacterial infective endocarditis
  7. Osteomyelitis
  8. Brucellosis

★ How do you Enrich blood culture media?

  1. Tryptic soy broth.
  2. Diphasic tryptone soya media.
  3. Bile salt with or without gentian violet
  4. Thioglycolate broth for growth of anaerobes
  5. Brain heart infusion broth

★ What is the purpose of Enrichment?

-Enrichment is done in blood culture, because very small numbers of bacteria are usually present in blood, enrichment of blood is done to rapidly increase bacterial count and perform subculture . This results in visible colonies are produced in solid media.

★ What media are used for subculture?

  • Sub-culture done in :
  1. Blood agar media
  2. Mac Conkey’s agar media
  3. Chocolate agar media

★ Procedure of Blood Culture :

  1. Traditional method :Using liquid media on biphasic media
  2. Lytic method : After processing in lytic solution in solid media
  3. Automated : Very rapid (within 6 hours)

This is all about Blood Culture.

Sushmita Chowdhury

Platform academic/Shultan Mahmud Jahid

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