[Pruebas diagnósticas in vivo en alergia inmediata a penicilina: estudio piloto].

Background: The most commonly reported antibiotic allergy is penicillin. The false label of "allergy" to penicillin negatively affects the patient's quality of life and medical care.

Objective: To determine the frequency of allergy to penicillin and amoxicillin by in vivo exposure tests in patients with a history of immediate reaction to this class of medicinal products.

Methods: Observational, cross-sectional, descriptive and prolective study in patients between 12 and 60 years of age with a history of immediate reaction to penicillin and/or amoxicillin. Prick and intradermal skin tests were performed with benzylpenicilloyl polylysine (Pre-Pen), penicillin G and oral challenge test with amoxicillin. The frequency of positivity and negativity in these tests was calculated with a 95% CI. Results were analyzed in Epi info 7.2.5.0.

Results: In total 13 patients (10 women) were included, with a mean age of 39 years (SD 12.14). In 84.6% the last adverse drug reaction occurred 10 years ago and in all manifested with urticaria. The 38.4% confirmed penicillin allergy and the most frequent adverse reaction after in vivo tests was pruritus.

Conclusions: The clinical history alone is not sufficient, all patients with suspected penicillin allergy should be evaluated by in vivo exposure tests with major and minor determinants to corroborate or rule out allergy to this pharmacological class.