Penicillins allergy negative history

Patients with a history of penicillin allergy should undergo skin testing with both peniciUoyl-polylysine and minor determinant mixtures. Patients with positive skin tests should be treated with another immunologically unrelated compound or should undergo desensitization. The management of patients with a negative skin test but a history of a severe IgE-mediated reaction has to be individualized options include the use of an alternative compound, desensitization, or the controlled administration of a test dose. 

Immunologic Of 85 patients with a history of penicillin allergy and positive penicillin skin tests 5 (6%) had an adverse drug reaction to a cephalosporin compared with 5 (0.7%) of 726 patients with a history of penicillin allergy but negative penidllin skin tests [7. Presumed IgE-mediated adverse reactions to the cephalosporins occurred in 2 (2%) of the former compared with only 1 (0.1%) of the latter. 

For those with a negative history of penicilUn allergy, the incidence of positive skin tests is 2-7 %. For skin test-positive patients given a therapeutic dose of penicillin, the risk of an acute allergic reaction ranges from 10 % in patients with a negative history to 50-70 % in patients with a positive history. 

Thus patients liable to an anaphylactic reaction to penicillin should be the ones with positive skin tests to BPL or the MDM. Clinical studies are bearing this out. Of 200 patients with past histories of penicillin allergy, 170 had negative skin tests and 30 had positive tests. The 170 skin-test negative patients tolerated penicillin without anaphylactic or urticarial allergic reactions. Of 9 skin test positive patients given penicillin by gradual administration, 7 had urticarial reactions (which... 

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