Cephalosporins allergy hypersensitivity

If a patient has a mild, delayed allergy to penicillin, first-generation cephalosporins are effective alternatives but should be avoided in patients with an immediate-type hypersensitivity reaction. 

Cephalosporins are sensitizing and may elicit a variety of hypersensitivity reactions that are identical to those of penicillins, including anaphylaxis, fever, skin rashes, nephritis, granulocytopenia, and hemolytic anemia. However, the chemical nucleus of cephalosporins is sufficiently different from that of penicillins so that some individuals with a history of penicillin allergy may tolerate cephalosporins. The frequency of cross-allergenicity between the two groups of drugs is uncertain but is probably around 5-10%. However, patients with a history of anaphylaxis to penicillins should not receive cephalosporins. 

The cephalosporins are contraindicated in patients with known allergies or intolerances to any of the cephalosporins. Because the penicillins and cephalosporins have a common chemical structure, cross-allergies occur with these drugs. Thus before initiating therapy with a cephalosporin, careful inquiry should be made concerning previous hypersensitivity reactions to the other drugs. Because a secondary vitamin K deficiency can develop with cephalosporin use, the cephalosporins are contraindicated in patients with hemophilia. Cefaclor is also contraindicated in any patient with previous drug-related joint and skin reactions. 

If a patient has a mild, delayed allergy to penicillin, first-generation cephalosporins (such as cefazolin) are effective alternatives, but they should be avoided in patients with a history of immediate-type hypersensitivity reactions to penicillins (see Table 109-6). The potential for a true immediate-type allergy should be assessed carefully, and a penicillin skin test should be conducted before giving antibiotic treatment to any patient claiming an allergy. 

Allergy Cephalosporins cause a range of allergic reactions from skin rashes to anaphylactic shock. These reactions occur less frequently with cephalosporins than with penicillins. Complete cross-hypersensitivity between different cephalosporins should be assumed. Cross-reactivity between penicillins and cephalosporins is incomplete (5-10%), so penicillin-allergic patients are sometimes treated successfully with a cephalosporin. However, patients with a history of anaphylaxis to penicillins should not be treated with a cephalosporin. 

Waldbott GL (1949) Anaphylactic death from penicillin. JAMA 139 526 Waldo JF, Tyson JT (1949) Hypersensitivity to penicillin. Am J Med 6 396 Walsh WE, Markowitz H, Jones JD, Gleich GJ (1971) Macromolecular contaminants in penicillin and cephalosporin antibiotics. J Allergy 47 159 Warrington RJ, Tse KS (1979) Lymphocyte transformation studies in drug hypersensitivity. Can Med Assoc J 120 1089... 

Romano A, Gaeta F, Valluzzi RL, et al. IgE-mediated hypersensitivity to cephalosporins cross-reactivity and tolerability of penicillins, monobactams, and car-bapenems. 1 Allergy Clin Immunol. 2010 126 994-9. 

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