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Background: In some diseases penicillin is the treatment of choice. Case studies have shown a good response for the treatment of circumscribed scleroderma or scleroderma adultorum of Buschke. A suspected allergy to penicillin in a patient's history may limit this helpful therapy option. Allergy testing is often inconclusive. If indicated, tolerance induction leading to therapy with penicillin can be carried out., Patients and Methods: We present two patients with circumscribed sclerosis and scleredema Buschke, who had a suspected allergy to penicillin. Due to limited therapy options and in insufficient response to other therapeutics, the decision for a tolerance induction with penicillin was made. Penicillin was successfully administered by following a scheme of tolerance induction starting with oral doses and ending with high doses of intravenous penicillin G., Results: In both cases, penicillin G, administered over a period of three weeks, was well tolerated up to the high dose of 3 x 10 Mega IU/day. Substantial clinical improvement was achieved in all cases without any complications., Conclusion: This case study demonstrates that a suspected allergy to penicillin does not preclude an eventual treatment with this valuable drug. Allergy testing should routinely be carried out first. If suspicion of an allergy persists, tolerance induction can be attempted according to the new scheme described here. Starting with a careful, initial oral dose regimen, treatment can be continued with an increasing intravenous dose followed by maintenance therapy with high-dose penicillin G. It should be clear that this policy is only restricted for patients who are at risk for a hypersensitivity to penicillin, i.e., because of a clinical manifested incompatibility in the past.

Background: Despite the widespread use of an acute oral desensitization procedure in patients with allergic reactions to a variety of antibiotics, the precise mechanism of this procedure is poorly understood., Objective: To investigate the mechanisms underlying acute oral desensitization to antibiotics., Methods: Using a murine model of active systemic anaphylaxis to penicillin V (Pen V), mice previously sensitized to Pen V were desensitized by oral feeding of Pen V. The dose was doubled every 15 min and five feedings were given. The achievement of acute oral desensitization was evaluated by induction of active systemic and active cutaneous anaphylaxis, and by measuring the plasma levels of platelet-activating factor and histamine. Antigen-specific serum IgE antibody (Ab) levels were determined by passive cutaneous anaphylaxis., Results: Mice fed more than 3 mg of cumulative dose of Pen V were completely protected from fatal systemic anaphylactic reaction and the desensitized state lasted approximately 1 h. Antigen-specific mast cell desensitization, but not hapten inhibition, consumption of IgE Abs, or depletion of mast cell mediators, occurred during acute oral desensitization., Conclusions: Acute oral desensitization to Pen V occurred in the mice, and antigen-specific mast cell desensitization was associated with the underlying mechanism for oral desensitization.

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.