Frequency of systematic reactions to penicillin skin tests

Penicillin skin testing is generally considered to be safe when performed sequentially with puncture and intradermal testing although fatalities have been reported.

We analyzed the rate of systemic reactions to penicillin skin tests for a period of seven and two-thirds years.

This retrospective study used a computerized database at the Mayo Clinic. Altogether 1710 patients were skin-tested to penicillin from January 1992 to September 1999. All patients tested had a history of penicillin allergy. Patients were tested with benzylpenicilloyl polylysine (Pre-Pen) (6.0 X 10(-5) M), freshly prepared penicillin G (10,000 units/ml), and penicilloate (0.01 M). Prick tests were done first and if negative then intradermal tests. Systemic reactions were evaluated and treated by physicians.

Eighty-six patients had positive penicillin skin tests of which two had systemic reactions. Our systemic reaction rate for all patients tested was 0.12%; and 2.3% for the penicillin skin test-positive group, with no fatalities.

The incidence of systemic reaction to penicillin skin tests is low. Skin prick tests should always be done first. If there is a history of a previous serious reaction, the skin tests-if done-should be diluted to start with. Those doing penicillin skin tests should be prepared to treat a systemic reaction.