EBQ:Cephalosporin Cross-reactivity

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Prior to 1980, penicillins(PCN) and cephaloporins were often produced using the same fungus and the chance for contamination during the manufacturing process of a cephalosporin with a PCN was high. The allergy was assumed to be due to the beta-lactam ring but was later determined to be due to the manufacturing process.

More recent studies have determined that the actual risk of cross-reactivity relates to side chain similarity and not the beta-lactam ring. 1st and 2nd generation penicillins share the same R-1 side chain and are more likely to exhibit cross reactivity. A current review of the literature demonstrates that the 10% or greater allergy that is commonly reported may be exaggerated.

  • 1st generation cephalosporins: cefadroxil, cefatrizine, cephalexin, cephradine
  • 2nd generation cephalosporins: cefaclor, cefprozil


Campagna Review Article

  • Overall cross-reactivity rate between cephalosporins and penicillins in patients reporting a penicillin allergy = 1%. [1]
  • Overall cross-reactivity rate in patients with a confirmed penicillin allergy = 2.5%.
  • Cross-reactivity between penicillins and 1st and 2nd generation cephalosporins is possible.
  • Cross-reactivity between penicillins and ALL 3rd and 4th generation cephalosporins is negligible.
  • If a patient has an allergy to amoxicillin or ampicillin, avoid cefadroxil, cefaclor, cefatrizine, cefprozil, cephalexin, and cephradine.

Sources

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

http://www.ncbi.nlm.nih.gov/pubmed?term=21742459