[Penicillin allergy as a diagnostic problem. Overview and personal studies].

BACKGROUND AND OBJECTIVE

Penicillin allergy is a common clinical problem. The distinction between penicillin and para-infectious exanthems is difficult. We investigated the reliability of the history, as well as the sensitivity and specificity of skin tests and specific IgE levels.

PATIENTS/METHODS: 160 patients with a history of penicillin allergy were retrospectively evaluated in the outpatient department of a dermatological clinic.

RESULTS

Nearly 50% were diagnosed as allergic to penicillin by detection of specific IgE or skin test. About 60% of the patients with immediate type reactions, and 72% with maculo-papular erythema showed positive reactions in skin tests. Significantly more patients were diagnosed as allergic to penicillin by intradermal testing than by prick testing (p < 0.05). The sensitivity of the specific IgE RAST was 17.9%; the specifity, 89.5%. For the prick test the sensitivity was 8.2%; the specificity 90.8%. For the intradermal test the sensitivity was 26%; the specifity 69.7%.

CONCLUSIONS

We suggest a step by step procedure to detect penicillin allergy making the diagnostic results as valid as possible.