Successful desensitization to penicillin after diagnostic reassessment

Clinical situations for which penicillin is indicated as the sole effective treatment are not infrequent, in these circumstances penicillin allergy complicates their medical management. No proven alternatives to penicillin are available for treating neurosyphilis, congenital syphilis, or syphilis in pregnant women, it is not possible choosing an alternative non betalactam antibiotic. The management of the patient who has a history of penicillin allergy include skin testing to determine if penicillin-specific IgE antibodies exist, and desensitization if penicillin is the choice treatment. We report a case of successful desensitization to penicillin in a 30 year-old pregnant woman with latent syphilis and penicillin allergy, where the first penicillin study was not positive, but the repetition of diagnosis test (reassessment) with the same betalactam reagents than in the first study two weeks later the initial evaluation was positive, detecting allergic sensitization not detected at the previous examination.