The use of cephalosporins in penicillin-allergic patients

Pichichero ME, Zagursky R. Penicillin and cephalosporin allergy. Ann Allergy Asthma Immunol. 2014 May;112(5):404-12.

“Conclusion: This evidence-based review teaches that the incidence of allergic reactions to penicillins is much lower than widely thought. Penicillin skin testing and FEIA is used for type I immune testing. Neither skin testing nor FEIA testing is of any value in detecting risk of type II to IV reactions. The classic approach for predictive penicillin allergy has been the skin test using penicilloyl polylysine and MDMs. If an ampicillin or amoxicillin allergy is suspected, then one may include ampicillin or amoxicillin to predict ampicillin-amoxicillin allergy. Currently, penicillin skin testing using only penicilloyl polylysine and penicillin followed by an oral challenge with amoxicillin is now considered to be adequate in evaluating a type I penicillin allergy. [31] Allergy to penicillins (and cephalosporins) is caused mainly by reactions to the side chains of themolecules and less commonly to the b-lactam ring.

Cephalosporin allergy in penicillin allergic patients is attributable to cross-reactive antibodies to side-chain similarity of the cephalosporin to penicillin or amoxicillin. Cephalosporin allergy may result from cross-reactivity among cephalosporin compounds if the R1 or R2 side chains of the cephalosporins are identical or similar. Anaphylaxis from cephalosporins is rare. There is no evidence of an increased risk of anaphylaxis to cephalosporins in penicillin-allergic patients. Likewise, there is little risk of allergy to carbapenems, monobactams, and b-lactamase inhibitors that lack identical or similar side chains to penicillin in penicillin allergic patients.”

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Campagna JD, Bond MC, Schabelman E, Hayes BD. The use of cephalosporins in
penicillin-allergic patients: a literature review. J Emerg Med. 2012 May;42(5):612-20.

Although a myth persists that approximately 10% of patients with a history of penicillin allergy will have an allergic reaction if given a cephalosporin, the overall cross-reactivity rate is approximately 1% when using first-generation cephalosporins or cephalosporins with similar R1 side chains. However, a single study reported the prevalence of cross reactivity with cefadroxil as high as 27%. For penicillin-allergic patients, the use of third- or fourth-generation cephalosporins or cephalosporins with dissimilar side chains than the offending penicillin carries a negligible risk of cross allergy.

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Pichichero ME, Casey JR. Safe use of selected cephalosporins in penicillin-allergic patients: a meta-analysis. Otolaryngol Head Neck Surg. 2007 Mar;136(3):340-7.

Many patients who present with a history of penicillin allergy have not had an immunologic reaction to a penicillin. In patients with a documented IgE-mediated reaction to a penicillin, use of cephalosporins with a similar side chain should be avoided. However, cephalosporins with different side chains may be given. These recommendations are based on the results of a systematic review, [5] this meta-analysis, and an understanding of the role of chemical structure in allergic cross-reactivity.

Full-text for Emory users.

More PubMed results on the use of cephalosporins in penicillin-allergic patients.

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