title: Immediate allergic reactions to cephalosporins: evaluation of cross-reactivity with a panel of penicillins and cephalosporins.
abstract: BACKGROUND
  Allergy to cephalosporins has mainly been evaluated in the context of patients with confirmed penicillin allergy. The problem of studying cross-reactivity in subjects primarily sensitized to cephalosporins and potentially allergic to penicillins has not been sufficiently addressed.
  
  
  OBJECTIVE
  To evaluate the in vitro IgE response and cross-reactivity to betalactams in patients with immediate allergic reactions to cephalosporins.
  
  
  METHODS
  The study included 24 patients with immediate allergic reactions to cephalosporins and RAST-positive to at least 1 cephalosporin. Skin testing and RAST were performed with a panel of penicillins and cephalosporins. RAST inhibition assay with different monomeric conjugates of penicillin and cephalosporin was performed to establish cross-reactivity.
  
  
  RESULTS
  The culprit cephalosporins were cefaclor (N = 7), cefonicid (N = 1), cefotaxime (N = 2), ceftazidime (N = 2), ceftriaxone (N = 3), and cefuroxime (N = 9). Two patients had a positive skin test result to penicillin determinants, and 22 patients had a negative result to penicillin determinants and tolerated benzylpenicillin administration. Of these 22, 19 had a positive skin test result to cephalosporins and divided into patients reacting only to the culprit cephalosporin (63.2%) and those reacting to more than 1 cephalosporin (36.8%). RAST and RAST inhibition studies confirmed that the side chain at the R1 position is crucial for recognition.
  
  
  CONCLUSIONS
  The R1 side chain rather than the betalactam structure, shared by penicillins and cephalosporins, seems to play a dominant role in determining the specificity of immunologic reactions to cephalosporins. Thus, penicillin can be administered safely to patients allergic to cephalosporins and with a negative skin test result to penicillin determinants.
authors.affiliation: Research Laboratory for Allergic Diseases, Carlos Haya Hospital, Malaga, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Antunez
authors.forename: Natalia
authors.initials: N
authors.lastname: Blanca-Lopez
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Torres
authors.forename: Cristobalina
authors.initials: C
authors.lastname: Mayorga
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Perez-Inestrosa
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Montañez
authors.forename: Tahia
authors.initials: T
authors.lastname: Fernandez
authors.forename: Miguel
authors.initials: M
authors.lastname: Blanca
mesh_terms: D000293:Adolescent; D000328:Adult; D000707:Anaphylaxis; D000918:Antibody Specificity; D002511:Cephalosporins / Q000009:adverse effects* / Q000737:chemistry / Q000276:immunology*; D002648:Child; D003429:Cross Reactions; D004342:Drug Hypersensitivity / Q000209:etiology; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000139:chemically induced*; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010406:Penicillins / Q000009:adverse effects / Q000737:chemistry / Q000276:immunology*; D011852:Radioallergosorbent Test; D012882:Skin Tests
chemical_list: D002511:Cephalosporins; D010406:Penicillins; D007073:Immunoglobulin E