ANAPHYLAXIS TO PENICILLINS AFTER NON-THERAPEUTIC EXPOSURE - AN IMMUNOLOGICAL INVESTIGATION

Background There are instances where individuals may come into contact with penicillins without being aware of it. This non-therapeutic expo sure from different sources may cause sensitization and even clinical manifestations in subjects allergic to penicillins. Objective To deter mine the capacity that inadvertent contact with penicillins may have i n inducing resensitization and symptoms in patients diagnosed as aller gic to penicillins who were followed over a long period of time after their initial evaluation. Methods A follow-up study of penicillin-alle rgic subjects who agreed to be regularly tested for in vitro and in vi vo control of their sensitivity. Skin tests were carried out with majo r and minor determinants of benzylpenicillin (BPO and MDM), amoxicilli n (AX), and ampicillin (AMP), and specific IgE antibodies were determi ned by radioallergosorbent test (RAST). A questionnaire was sent to an d answered by the subjects in order to see if they experienced symptom s at any time during the follow-up period. In addition, if any unexpla ined symptoms occurred, a bleeper system was used to contact the aller gy centre. Results Seven subjects experienced anaphylactic reactions w ith no obvious cause. At the time of their initial allergic reaction, which was caused by exposure to prescribed penicillin. the subjects ha d one or more positive skin tests and/or RAST results to penicillin re lated reagents. However, over the following 2-4 years all their tests became negative. After reporting their unexplained reaction all seven had one or more positive skin tests and/or RAST results again and when retested 1 week later RAST measurements showed that levels of penicil lin-specific IgE were maintained or increased. None of the subjects ha d knowingly received penicillin but the questionnaire showed that six had been exposed to it and in the seventh case exposure was likely. In two cases contact was by sexual intercourse with a partner who was re ceiving penicillin, three subjects had handled penicillin formulations and one had drunk from a glass previously used for giving penicillin. In the seventh case exposure could have occurred whilst in hospital f or surgery, although this was not proven. Conclusions these results sh ow that non-therapeutic exposure to penicillin can cause severe sympto ms and that in vitro and in vivo testing can help in the diagnosis of such cases.