[Skin tests in patients with history of anaphylactic reaction to penicillin]

Skin tests including immediate patch test (IPT), skin prick test (SPT), or intradermal test (IT) with penicillin G(PenG) and SPT with benzylpenicilloyl human serum albumin (BPO) were done in 54 patients with history of anaphylactic reaction to penicillin or shock of unknown cause. 26 patients with penicillin allergy were diagnosed. BPO specific IgE measured with ELISA gave a lower positive rate in detecting penicillin allergy as compared with the tests mentioned above. The results of skin tests in 26 patients showed that IPT with 500 IU/ml of PenG was not only accurate but also safe. Because no skin injury occurred and PenG residue could be washed out, the amount of PenG penetrated into skin is very small, thus, adverse reactions were very few. It is recommended that IPT with PenG in 500 IU/ml concentration is performed at the beginning of skin tests. If negative, SPT and then IT both with a solution of 500 IU/ml concentration are carried out, until a positive reaction occurs. This procedure is relatively accurate, simple and safe.