Method for preparing stable .beta.-lactam-type-antibiotic susceptibility test discs

A method for preparing heat stable .beta.-lactam-type-antibiotic susceptibility test discs comprising the steps of:

• a. reducing the crystals of .beta.-lactam-type-antibiotic selected from the class consisting of penicillin G, penicillin V, ampicillin, cephalothin, cephaloridine, cephaloglycin, cephalexin, cef azolin, cef amandole, and cefoxitin in their pharmaceutically acceptable form to a size such that all pass a 100 mesh U.S. screen;
• b. dispersing the antibiotic of (a) in a volatile unreactive non-solvent vehicle having a boiling point at or below 100.degree.C. at 760 mm of mercury;
• c. uniformly contacting clean white paper weighing from 26 to 34 mg/cm.sup.2 and having an absorbtive capacity of 2 to 3 times its own weight of distilled water with the dispersion of (b), the dispersion being contacted with such paper being in an amount that will deposit a susceptibility testrequired quantity of the antibiotic of (a) on each area of such paper corresponding to the area of a susceptibility test disc;
• d. evaporating the non-solvent vehicle from the paper of (c);
• and
• e. forming individual susceptibility test discs from the paper of (d), each of such discs having an area corresponding to the area of such paper having deposited thereon a susceptibility test required amount of the antibiotic.