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Principle
- The media is composed according to the USP, recommended as an antibiotic assay medium. It is composed of peptone, yeast extract, meat extract, sodium chloride, dextrose, dibasic potassium phosphate, and monobasic potassium phosphate. Peptone, yeast extract and meat extract provide nitrogen, carbon, vitamins essential nutrients.
- Sodium chloride maintains osmatic balance in the medium. Dextrose serves as an energy source. Dibasic and monobasic potassium phosphate acts as buffing agent.
- The media is used for estimating the concentration of antibiotics by biological assay or turbidimetric antibiotic assay for a clear solution only.
- A uniform concentration of microorganism suspension is inoculated in a series of antibiotic assay mediums (5-10 ml) containing working dilution of antibiotic (varying concentration of antibiotic).
- After incubation, the amount of growth is determined by measuring the light transmittance using a spectrophotometer. The concentration of antibiotic is estimated by associating amounts of growth obtained with the given by the reference standard solutions.
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