Penicillins are the most consumed antibiotics in Europe, representing 37% of total consumption, followed by cephalosporins with a 15% of total antibiotic consumption. The synthetic determinants of CX, 1 -(HOPhG-Ser-Bu) and 2 -(pyrazinone) are promising tools for determining in vitro cross-reactivity to CX in AX allergic patients.Ĭhemical structures of betalactam antibiotics involved in the study: amoxicillin (AX), cefadroxil (CX), and cefuroxime (CO) with indication of the different parts of the structures R1, although critical for recognition, is not the unique factor. ConclusionsĬross-reactivity with CX in AX allergic patients is 35%, being ST not enough for prediction. RAST inhibition assays showed higher recognition to CX as well as to both synthetic determinants (66% of positive cases) in Group B. ST to CX showed a negative predictive value of 94.6%. Cross-reactivity with CO was only found in 1.8% cases from Group B. Tolerance to CX (Group A) was observed in 64.8% cases and cross-reactivity in 35.2% cases (Group B). Two potential determinants of CX, involving intact or modified R1 structure, with open betalactam ring, were synthesised and sIgE evaluated by RAST inhibition assay. Serum sIgE to AX and benzylpenicillin was determined by Radioallergosorbent test (RAST).
Methodsįifty-four patients with confirmed IHRs to AX based on skin test (ST) and/or drug provocation test (DPT) were included. We aimed to analyse cross-reactivity with CX and CO in patients with confirmed IHRs to AX, including sIgE recognition to AX, CX, CO, and novel synthetic determinants of CX.
Amoxicillin (AX) is the betalactam most often involved in immediate hypersensitivity reactions (IHRs), and cefadroxil (CX) the most likely cephalosporin to cross-react with AX, since they share the same R1 side chain, unlike cefuroxime (CO), with a structurally different R1. Analysis of cross-reactivity is necessary for prescribing safe cephalosporins for penicillin allergic patients.