SEVERE ANAPHYLAXIS FROM RIFAMYCIN SV

Background: Anaphylaxis to topical application of rifamycin SV, which is used topically in the fields of surgery and dermatology, is rare. M ethods: We report two cases of systemic reactions occurring after loca l administration of rifamycin (Rifocine, Gruppo Lepetit, Italy). Both of them needed repeated intermittent topical applications. Skin prick tests with Rifocine constituents were performed on our patients, and a lso on ten atopic and ten nonatopic subjects. Although an old investig ative tool, Prausnitz-Kustner (P-K) test was also performed on one of the patient's spouses to show passive transfer and the IgE-mediated me chanism. Results: Allergy assessment with skin tests on the patients w ere negative for aeroallergens, latex, and Rifocine constituents (exce pt rifamycin SV). The patients' prick tests with rifamycin SV were pos itive, and the control subjects were negative. P-K testing was positiv e. Conclusion: Two case reports support the existence of IgE-mediated reactions to rifamycin SV. IgE-mediated anaphylactic reactions from ri famycin SV appear to be extremely rare.