A Comparison of the Value of Clarase, Penicillinase, and Cysteine Hydrochloride in Revealing the Presence of Contaminating Organisms in Preparations of Penicillin

Under the experimental conditions used clarase appeared to be more satisfactory for use in the routine testing of sterility of solutions of penicillin than penicillinase or cysteine hydrochloride. Purified penicillinase was only slightly less effective than clarase and, because of the ease of sterilization, it might prove to be the better agent if obtainable in large amounts. While cysteine is capable, under certain conditions, of destroying quickly large amounts of penicillin inconstant results may be obtained because of its instability. Another disadvantage in the use of cysteine is its bacteriostatic action against certain organisms in a concentration necessary for inactivation of penicillin.