title: The Importance of Amoxicillin and Amoxicillin-Clavulanate Determinants in the Diagnosis of Immediate Allergic Reactions to β-Lactams.
abstract: BACKGROUND
  Immediate allergic reactions to β-lactam antibiotics are considered to be one of the most important drug hypersensitivities. A positive skin test (ST) with a combination of major and minor penicillin determinants is usually sufficient to recommend avoidance of the culprit drug, whereas a negative ST is usually followed by an oral challenge test (OCT). Recently, concern has been raised regarding the role of amoxicillin (AMX) ST in the diagnosis of AMX allergy.
  
  
  OBJECTIVE
  The aim of this study was to examine the additive value of AMX determinants in STs of patients with immediate hypersensitivity reactions to AMX or AMX-clavulanate (AMX-C).
  
  
  METHODS
  Patients with a history of immediate AMX or AMX-C allergy underwent an ST using a combination of penicilloyl-polylysine (PPL) and minor determinants as well as AMX. An ST with AMX-C was added when appropriate.
  
  
  RESULTS
  Thirty-one patients were evaluated. Eight patients, all of them with a history of AMX allergy, had positive reactions only to the AMX component. Two patients with AMX-C allergy had a positive ST reaction only to the AMX-C component. Moreover, only 14 patients (13 with AMX and 1 with AMX-C allergy) had a positive reaction to PPL, whereas most patients (54.8%) had positive reactions to other determinants. One patient, who was positive for AMX, developed several urticarial lesions after the test.
  
  
  CONCLUSIONS
  Skin testing with AMX and AMX-C is mandatory in patients with immediate allergy to these drugs. Failure to perform it may result in a false-negative ST jeopardizing these patients with anaphylactic reactions during a hazardous OCT.
authors.affiliation: Allergy and Clinical Immunology Unit, Meir Medical Center, Kfar Saba, Israel.
authors.forename: Ronit
authors.initials: R
authors.lastname: Confino-Cohen
authors.forename: Yossi
authors.initials: Y
authors.lastname: Rosman
authors.forename: Idit
authors.initials: I
authors.lastname: Lachover
authors.forename: Keren
authors.initials: K
authors.lastname: Meir Shafrir
authors.forename: Arnon
authors.initials: A
authors.lastname: Goldberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000276:immunology*; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D004342:Drug Hypersensitivity / Q000175:diagnosis* / Q000276:immunology*; D000939:Epitopes / Q000276:immunology*; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis* / Q000276:immunology*; D007223:Infant; D008297:Male; D008875:Middle Aged; D012882:Skin Tests; D055815:Young Adult; D047090:beta-Lactams / Q000009:adverse effects*
chemical_list: D000939:Epitopes; D047090:beta-Lactams; D019980:Amoxicillin-Potassium Clavulanate Combination; D000658:Amoxicillin