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Veterinary bacteriology: information about important bacteria
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Tryptic soy agar (TSA) + VRG

Tryptic soy agar (TSA)

The image shows a combined TSA and VRG agar plate. On plate A, no bacteria have been streaked out, while Escherichia coli has been streaked out on plate B. - Click on the image to enlarge it.


"Tryptic soy agar (TSA)" is a general medium, which is used for isolation and enumeration of many different bacteria, among others, E. coli.

The medium contains:

  • casein peptone (contains amino acids and peptides)
  • soya peptone (contains amino acids and peptides)
  • NaCl (contributes to the osmotic balance)
  • agar (gelifying agent)
  • water

The final pH of the medium should be 7.3.

Other comments:

TSA is often used in combination with VRG agar. TSA is then mixed with the sample to be analyzed at around 40°C and poured into the plates. After preincubation for 1-2 h at ambient temperature, the TSA is overlayed with VRB agar and the incubation is then continued at 37°C.

Updated: 2023-05-31.

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