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TYPE OF MEDIA

  • Basal Media
  • Enriched Media
  • Selective Media
  • Enrichment Media
  • Differential Media
  • Transport Media

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BASAL MEDIA

  • these are culture media which contain basic nutritional requirements for the growth of non-fastidious bacteria
  • these may be liquid or solid eg Nutrient agar, peptone water and sabouraud dextrose agar ( scrapping sample) expected organism family of Enterobacteriacae: Escherichia coli , salmonella species .
  • Nutritionally non- demand eg staphylococcus species

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ENRICHED MEDIA

  • basal media which have been supplemented with additional growth enhancing substances such as fluid ( blood, serum, ascetic fluid) blood agar, chocolate agar.
  • It encourages fastidious organism eg Haemofilus influenza, Neisseria spp

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SELECTIVE MEDIA

  • Some media are useful because they do not support the growth of certain bacteria species Desoxycholate citrate agar ( DCA ) SS agar.
  • it contains sodium citrate 1%, ferric citrate 0.1%, sodium desoxycholate 0.5%, neutral red 0.0002%, and agar 1.5%. the sodium desoxycholate ( bile salt) content inhibit the growth of non-enteric spcies
  • while enteric species are salmonella spp, Shigella

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ENRICHMENT MEDIA

  • An enrichment medium is a liquid medium in which some bacteria species can outgrowth others.

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  • It contains substance which inhibit the growth of unwanted species while the want ones growth e.g selenite F broth

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DIFFERENTIAL MEDIA

  • are solid media which different bacteria species may be distinguished by their different form of growth.
  • MacConkey agar and Cystein-Lactose-electrolyte deficient agar.
  • MCA contains neutral red which served as an indicator, it support the growth of enterobacteria
  • Lactose-fermenting bacteria such as Escherichia coli form red colonies or pale
  • Non- lactose fermenting bacteria such as salmonella, shigella form colourless colonies

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DIFFERENTIAL MEDIA CONT’D

  • CLED contains Bromothymol blue which served as an indicator, lactose fermenter appear yellow and non-lactose fermenters appear blue,
  • it contains L-cystine which enhance the growth of cystein dependend lactose fermenting organism e.g E coli,
  • it is particularly recommended for diagnostic of urinary infection because it supports the growth of all urinary potential pathogens
  • Blood agar- haemolytic and non haemolytic bacteria

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TRANSPORT MEDIA

  • transport media are used for transportation or storage of clinical materials from which particular organisms are subsequently to be isolated e.g Stuart’s transport medium.
  • Samples are urethral swab and ECS.
  • phosphate buffered , glycerol saline , carry- Blair medium samples are stool, blood and mucus

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