Challenge of penicillin-allergic volunteers with penicillin-contaminated meat.

In order to obtain information about the clinical course and immunological background of possible allergic reactions due to penicillin-containing food, nine volunteers with penicillin allergy proved by case history, positive skin tests and/or positive penicilloyl-specific RAST were exposed to penicillin-contaminated pork. For this purpose a farm pig from an inbred strain received "therapeutic" doses of benzyl procain penicillin before being slaughtered. Meat samples were taken from muscle tissues, kidney and liver and analyzed by diffusion and extraction methods. Very small amounts of penicillin were detectable in muscle tissue, whereas kidney material contained up to five times as much (0.12 mcg/g). Except two cases which reacted with itchy sensations after ingestion of penicillin contaminated meat "á la tartare", all probands were clinically free of symptoms. Assaying penicilloyl-specific IgE antibodies by RAST during the trial, a tendency to increased levels in the serum after 2 and 24 h was noted, whereas the titers of BPO-specific IgG antibodies measured by the red cell-linked antigen-antiglobulin reaction (RCLAAR) remained unchanged. It is concluded from this study that small and hidden amounts of penicillin and its derivatives in food seldom induce anaphylactic reactions in penicillin allergic patients.