title: Retrospective case series analysis of penicillin allergy testing in a UK specialist regional allergy clinic.
abstract: BACKGROUND
  Penicillin allergy is the most common drug allergy. Skin testing for the major (PPL) and minor determinants (MDMs) of penicillin offers increased sensitivity and specificity over in vitro testing alone. Following a worldwide absence of reagents, a new kit was licensed in the UK in 2008 (Diater, Spain) and this report evaluates its use in a UK specialist allergy clinic.
  
  
  METHODS
  Prospective data on 50 consecutive patients tested with the new reagents were collected. The departmental protocol is adapted from the 2003 EAACI position paper.
  
  
  RESULTS
  14% (7/50) and 12% (6/50) of patients were diagnosed with immediate and non-immediate reactions respectively. The negative predictive value of the PPL and MDM reagents at the neat concentration for an immediate reaction was 93% (true negatives 37, false negatives 3). Two patients experienced systemic reactions to DPT in the absence of demonstrable specific IgE. None of the patients were diagnosed using skin prick testing alone or at lower concentrations of IDT. Five patients were diagnosed at the IDT stage and two at the DPT stage in the absence of demonstrable specific IgE. Six patients were diagnosed with non-immediate reactions, two on IDT alone and four following IDT and DPT.
  
  
  CONCLUSIONS
  The new PPL and MDM determinants offer enhanced sensitivity when evaluating β-lactam hypersensitivity; however, there are limitations to the current testing regimens. The UK would benefit from local guidelines, which incorporate the new reagents and acknowledge the high amoxicillin prescription rate and the relatively lower specialist-to-patient ratio in this country.
authors: Department of Clinical Immunology, Birmingham Heartlands Hospital, Birmingham, UK. richter@heartofengland.nhs.uk
authors: A G
authors: AG
authors: Richter
authors: G
authors: G
authors: Wong
authors: S
authors: S
authors: Goddard
authors: J
authors: J
authors: Heslegrave
authors: C
authors: C
authors: Derbridge
authors: S
authors: S
authors: Srivastava
authors: L
authors: L
authors: Diwakar
authors: A P
authors: AP
authors: Huissoon
authors: M T
authors: MT
authors: Krishna
mesh_terms: D000328:Adult; D000553:Ambulatory Care; D004342:Drug Hypersensitivity / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008297:Male; D008875:Middle Aged; D010406:Penicillins / Q000009:adverse effects*; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012882:Skin Tests / Q000379:methods
chemical_list: D007074:Immunoglobulin G; D010406:Penicillins; D011933:Reagent Kits, Diagnostic