The authors present 2 case reports of selective cefazolin hypersensitivity: a 49 year-old woman with a history of two perioperative reactions (urticaria and severe anaphylaxis) after the use of rocuronium, propophol and cefazolin; a 36 year-old pregnant woman who developed facial erythema, lips angioedema and hypotension immediately after administration of ropivacain, sufentanil, cefazolin, oxytocin and ephedrine. In both cases, intradermal skin tests were positive for cefazolin. A basophil activation test was performed for cefazolin, which was positive in one patient. Oral challenge tests with penicillin, amoxicillin and other cephalosporins were negative. This selective hypersensitivity to cefazolin may be associated with a R1-side chain different from other beta-lactams.
Keywords: R1 side chain; basophil activation test; cefazolin; selective hypersensitivity.