Real-Life Application of the Penicillin Allergy Decision Rule (PEN-FAST) Score in De-Labeling Penicillin Allergy: A...

Penicillin allergies are common but frequently inaccurate, resulting in unnecessary use of broad-spectrum antibiotics and contributing to antibiotic resistance. Tools such as the Penicillin Allergy Decision Rule (PEN-FAST) support the assessment of penicillin allergy risk and can help identify low-risk individuals who may be appropriate candidates for a direct oral penicillin challenge. We report four cases of patients hospitalized with respiratory infections, including infective exacerbation of bronchiectasis, bronchopneumonia, and empyema thoracis, all with documented penicillin allergy labels. In each case, a more detailed review of the allergy history revealed reactions inconsistent with IgE-mediated hypersensitivity reactions, including isolated diarrhea, leg swelling, and delayed rashes. All patients had a PEN-FAST score of 0, which indicated a low risk of a true penicillin allergy. These patients underwent supervised direct oral challenges with amoxicillin or co-amoxiclav, which revealed no adverse reactions. Following a successful oral challenge, penicillin allergies were de-labeled, and the patients were started on optimal antibiotic treatment. All cases revealed favorable outcomes, such as improvements in inflammatory markers and symptoms.