Things We Do For No Reason: Failing to Question a Penicillin Allergy History

Inspired by the ABIM Foundation’s Choosing Wisely® campaign, the “Things We Do for No Reason” (TWDFNR) series reviews practices that have become common parts of hospital care but may provide little value to our patients. Practices reviewed in the TWDFNR series do not represent “black and white” conclusions or clinical practice standards but are meant as a starting place for research and active discussions among hospitalists and patients. We invite you to be part of that discussion.

An 80-year-old male—with a past medical history significant for hypertension, atrial fibrillation, and type II diabetes mellitus—presented to the hospital with fevers, confusion, and urinary outflow tract difficulties. On exam, he was noted to have mild suprapubic tenderness with flank tenderness. Blood and urine cultures grew Enterococcus faecalis sensitive to ampicillin. Because of the patient’s listed penicillin (PCN) allergy, he was started on aztreonam and vancomycin instead of ampicillin.

Ten percent of the population in the United States reports an allergy to penicillin and derivatives—one of the most commonly reported drug allergies.¹ Allergic reactions to drugs are distinct immune reactions mediated by drug-specific immunoglobulin E (IgE) that are potentially life-threatening. Specifically these allergic reactions are called IgE-mediated, type 1 hypersensitivity reactions which are characterized by hives; itching; flushing; tissue swelling, especially in areas of the face and neck; bronchospasm; and gastrointestinal (GI) symptoms, including cramping and diarrhea. Head and neck swelling can quickly result in airway compromise. Profound fluid extravasation and release of mediators from mast cells and basophils can rapidly drop blood pressure. Anaphylaxis requires rapid intervention to prevent severe complications and death. Given the life-threatening consequences of anaphylaxis, a cautious approach before administering PCN to PCN-allergic patients is mandatory.

WHY YOU SHOULD QUESTION A REPORTED PCN ALLERGY

While 10% of the adult population and 15% of hospitalized adults report PCN allergy, clinical studies suggest that 90% of all patients reporting a PCN allergy can tolerate PCN antibiotics.^1-3 There are several reasons patients initially labeled as PCN allergic may later be able to tolerate this drug. First, patients can lose sensitivity to specific PCN IgE antibodies over time if PCN is avoided.⁴ Second, non-IgE-mediated immune reactions of skin or GI tract are often wrongly attributed to an IgE-mediated process from a concurrent medication (Table). For example, viral infections can cause exanthems or hives which may be mistaken for an antibiotic-associated IgE-meditated allergic reaction.⁶ These non-IgE skin reactions include severe manifestations including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis or benign adverse reactions such as GI upset, dizziness, or diarrhea which are often misclassified as an allergy, and this error is perpetuated in the medical record. Third, patients may report a PCN allergy for themselves when a family member is possibly allergic.