Antibiotic HiVeg™ Assay Medium No. 20 (Yeast HiVeg™ Broth)

Principle And Interpretation

Antibiotic HiVeg Assay Medium No. 20 is prepared by incorporating vegetable peptones in place of animal peptones, making the medium BSE, TSE risks free. This can be used for the same purpose of Antibiotic Assay Medium No. 20 (Yeast beef broth), used in the assay of various antibiotics. Grove and Randall have elaborately elucidated the methods to perform these assays and various media used for that (1). Schmidt and Moyer have reported the use of antibiotic assay medium for the liquid formulation used in the performance of antibiotic assay (2). These media are also recommended by USP (3) and FDA(4).

This medium can be used for the turbidometric assay of Amphotericin B using Candida tropicalis ATCC 13803 as test organism and also in the assay of mycostatic activity in pharmaceutical preparations.

High nutritional content like HiVeg peptone, yeast extract, HiVeg extract and HiVeg hydrolysate provides excellent medium for growth of Candida tropicalis. Dextrose provides carbon and energy for growth of the organism. Osmotic equilibrium to maintain cell intergrity and viability is provided by sodium chloride, while phosphate functions to provide proper buffering action.

Turbidimetric antibiotic assay is based on the change or inhibition of growth of a test microorganism in a liquid medium containing a uniform concentration of an antibiotic. After incubation of the test organism in the working dilutions of the antibiotics, the amount of growth is determined by measuring the light transmittance using spectrophotometer. The concentration of antibiotic is determined by comparing amounts of growth obtained with that given by the reference standard solutions. Use of this method is appropriate only when test samples are clear.