ANTIBIOTIC MEDIUM Nº 8 (BASE AGAR WITH LOW pH) 500 grams/bottle

Antibiotic Medium  Nº 8 is the standard agar base used for the microbiological assay of antibiotics like tetracycline due to its lower pH. The activity (potency) of an antibiotic can be demonstrated under suitable conditions by its inhibitory effect on microorganisms. Reduction in antimicrobial activity may reveal changes not demonstrated by chemical methods. The antibiotic media are identified numerically with names assigned by Grove and Randall in Assay methods of antibiotics. The use of standardized culture media and strict control of all test conditions are essential requirements in the microbiological assay of antibiotics in order to obtain satisfactory test results. This medium has the same formula as Antibiotic Medium  Nº 5 (Cat. 1524) and Antibiotic Medium  Nº 2 (Cat. 1002), with the difference that the pH of the medium has been adjusted to 5,7. To carry out the antibiotic test, the Antibiotic Medium should be prepared on the same day as the test is done. The sample can be tested by the two methods of dilution and assay plate diffusion. Gelatin peptone and beef extract provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is source of vitamins, particularly the B-group. Bacteriological Agar is the solidifying agent.