 Five 5 adult subjects without a history of penicillin allergy and fifteen 15 adult subjects with a history of penicillin allergy and previous positive penicillin skin test to the minor determinant penicilloate andor major determinant penicilloyl will be enrolled into the study. Each subject will be skin tested with our current penicillin skin test which includes penicilloate conducted in the Division of Allergic Diseases will be compared the skin test of our penicilloate prepared by our newer method along with the different diastereoisomers of penicilloic acid on the same day and time. The adult subjects without a history of penicillin allergy will serve as our control. 