title: Safely diagnosing clinically significant penicillin allergy using only penicilloyl-poly-lysine, penicillin, and oral amoxicillin.
abstract: BACKGROUND
  Penicillin skin testing is rarely used to undiagnose penicillin "allergy" in the United States, partially because of concern that commercially available materials are inadequate.
  
  
  OBJECTIVE
  We determined whether skin testing with only commercially available penicilloyl-poly-lysine and penicillin followed by an oral amoxicillin challenge, if skin test-negative, can safely identify clinically significant penicillin allergy.
  
  
  METHODS
  Five hundred sequential persons with positive history of penicillin "allergy" were evaluated by skin testing with penicilloyl-poly-lysine and penicillin between June 8, 2010, and March 29, 2012. All persons with negative skin tests were given an oral amoxicillin challenge and observed for 1 hour.
  
  
  RESULTS
  Persons undergoing penicillin allergy testing were representative of all health plan members with penicillin allergy. Only 4 persons (0.8%; 95% CI, 0.32%-2.03%) had a positive skin test result. Only 4 persons (0.8%; 95% CI, 0.32%-2.03%) had an acute objective oral amoxicillin challenge reaction. Fifteen persons (3.0%; 95% CI, 1.83%-4.98%) had subjective oral challenge reactions, either acute transient itching or dizziness. All were women and 11 (73.3%) had multiple drug intolerance syndrome. None had severe reactions or objective signs. These were not considered to be positive challenge reactions. Sixty-eight subjects (13.6%) who were negative on testing were exposed to 88 courses of penicillins during 90 days of follow-up. New reactions were reported after 4 courses (4.5%), 3 (75%) occurring in subjects with multiple drug intolerance syndrome.
  
  
  CONCLUSIONS
  Penicillin skin testing, using only penicilloyl-poly-lysine and penicillin, followed by oral amoxicillin challenge, if negative, can safely identify clinically significant IgE-mediated penicillin allergy in patients who use health care in the United States at this time.
authors.affiliation: Department of Allergy, Southern California Permanente Medical Group, San Diego Medical Center, San Diego, Calif. Electronic address: eric.m.macy@kp.org.
authors.forename: Eric
authors.initials: E
authors.lastname: Macy
authors.affiliation: Department of Research and Evaluation, Kaiser Permanente Health Care Program, Pasadena, Calif.
authors.forename: Eunis W
authors.initials: EW
authors.lastname: Ngor
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000008:administration & dosage / Q000009:adverse effects*; D044482:Benzeneacetamides / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010397:Penicillanic Acid / Q000009:adverse effects / Q000031:analogs & derivatives*; D010406:Penicillins / Q000009:adverse effects*; D011107:Polylysine / Q000009:adverse effects / Q000031:analogs & derivatives*; D011446:Prospective Studies; D012189:Retrospective Studies; D012882:Skin Tests; D055815:Young Adult
chemical_list: D044482:Benzeneacetamides; D010406:Penicillins; D011107:Polylysine; C003058:penicilloyl polylysine; D000658:Amoxicillin; D010397:Penicillanic Acid
keywords: Adverse reaction; Allergy; Amoxicillin; Antibiotic; Multiple drug intolerance syndrome; Oral challenge; Penicillin; Penicilloyl-poly-lysine; Skin test