β-lactam allergy
From IDWiki
Cross-Reactivity
- Cross-reactivity between penicillins and cephalosporins is mediated by homology of the R1 side chains, referring to the C6 side chain in penicillins or the C7 side chain in cephalosporins
- Cross-reactivity within cephalosporins is mediated both by homology of the R1 side chains and also R2 side chains, referring to the C3 side chain
| Antibiotic | R1 | R2 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| G1 | G2 | G3 | G1 | G2 | G3 | G4 | G5 | G6 | G7 | |
| Penicillin | X | |||||||||
| Ampicillin | X | |||||||||
| Amoxicillin | X | |||||||||
| Cefazolin | ||||||||||
| Cephalexin | X | X | ||||||||
| Cefadroxil | X | X | ||||||||
| Cephalothin | X | X | ||||||||
| Cefotetan | X | |||||||||
| Cefoxitin | X | X | ||||||||
| Cefuroxime | X | |||||||||
| Cefaclor | X | |||||||||
| Cefotaxime | X | X | ||||||||
| Ceftriaxone | X | |||||||||
| Ceftazidime | X | |||||||||
| Cefixime | X | |||||||||
| Cefdinir | ||||||||||
| Cefipime | X | |||||||||
| Ceftaroline | ||||||||||
R1 Side Chains (C6 and C7)
- Group 1: penicillin, cephalothin, cefoxitin
- Group 2: amoxicillin, ampicillin, cefaclor, cephalexin, cefadroxil
- Group 3: cefipime, cefotaxime, ceftriaxone
R2 Side Chains (C3)
- Group 1: cefadroxil, cephalexin
- Group 2: cefotetan
- Group 3: cefotaxime, cephalothin
- Group 4
- Group 5: cefuroxime, cefoxitin
- Group 6: cefixime
- Group 7: ceftazidime
Hypersensitivity Reactions
- Type I (IgE-mediated)
- Anaphylaxis
- Itchy rash
- Penicillins should be avoided
- Type II (IgG-mediated)
- Non-itchy rash
- Rash will improve if treatment continues, no need to avoid penicillins
- Type IV (cell-mediated)
- Toxic epidermal necrolysis
- Stevens-Johnson syndrome
- Penicillins should be avoided
Further Reading
- Zagursky RJ and Pichichero ME. Cross-reactivity in β-Lactam Allergy. J Allergy Clin Immunol Pract. 2018;6(1):72-81.e1. doi: 10.1016/j.jaip.2017.08.027
