title: Improving Clinical Outcomes in Patients With Methicillin-Sensitive Staphylococcus aureus Bacteremia and Reported Penicillin Allergy.
abstract: BACKGROUND
  Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia is a morbid infection. First-line MSSA therapies (nafcillin, oxacillin, cefazolin) are generally avoided in the 10% of patients reporting penicillin (PCN) allergy, but most of these patients are not truly allergic. We used a decision tree with sensitivity analyses to determine the optimal evaluation and treatment for patients with MSSA bacteremia and reported PCN allergy.
  
  
  METHODS
  Our model simulates 3 strategies: (1) no allergy evaluation, give vancomycin (Vanc); (2) allergy history-guided treatment: if history excludes anaphylactic features, give cefazolin (Hx-Cefaz); and (3) complete allergy evaluation with history-appropriate PCN skin testing: if skin test negative, give cefazolin (ST-Cefaz). Model outcomes included 12-week MSSA cure, recurrence, and death; allergic reactions including major, minor, and potentially iatrogenic; and adverse drug reactions.
  
  
  RESULTS
  Vanc results in the fewest patients achieving MSSA cure and the highest rate of recurrence (67.3%/14.8% vs 83.4%/9.3% for Hx-Cefaz and 84.5%/8.9% for ST-Cefaz) as well as the greatest frequency of allergic reactions (3.0% vs 2.4% for Hx-Cefaz and 1.7% for ST-Cefaz) and highest rates of adverse drug reactions (5.2% vs 4.6% for Hx-Cefaz and 4.7% for ST-Cefaz). Even in a "best case for Vanc" scenario, Vanc yields the poorest outcomes. ST-Cefaz is preferred to Hx-Cefaz although sensitive to input variations.
  
  
  CONCLUSIONS
  Patients with MSSA bacteremia and a reported PCN allergy should have the allergy addressed for optimal treatment. Full allergy evaluation with skin testing seems to be preferred, although more data are needed.
authors.affiliation: Division of Rheumatology, Allergy, and Immunology, Department of Medicine Medical Practice Evaluation Center, Massachusetts General Hospital Harvard Medical School.
authors.forename: Kimberly G
authors.initials: KG
authors.lastname: Blumenthal
authors.affiliation: Medical Practice Evaluation Center, Massachusetts General Hospital Harvard Medical School Biostatistics Center, Department of Medicine, Massachusetts General Hospital, Boston.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Parker
authors.affiliation: Medical Practice Evaluation Center, Massachusetts General Hospital Harvard Medical School Infection Control Unit Division of Infectious Disease, Department of Medicine.
authors.forename: Erica S
authors.initials: ES
authors.lastname: Shenoy
authors.affiliation: Medical Practice Evaluation Center, Massachusetts General Hospital Harvard Medical School Division of Infectious Disease, Department of Medicine.
authors.forename: Rochelle P
authors.initials: RP
authors.lastname: Walensky
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects / Q000627:therapeutic use; D016470:Bacteremia / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D020000:Decision Support Systems, Clinical; D004342:Drug Hypersensitivity / Q000150:complications* / Q000453:epidemiology; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus; D008954:Models, Biological; D015233:Models, Statistical; D010406:Penicillins / Q000009:adverse effects*; D013203:Staphylococcal Infections / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins
keywords: Staphylococcus aureus; allergy; decision analysis; penicillin; vancomycin