Penicillin allergy is the most commonly reported antibiotic allergy. Avoidance of β-lactam antibiotics in hospitalized patients leads to use of second line therapies. The utility of a penicillin allergy screening algorithm (PASA) and subsequent penicillin skin testing (PST) in transitioning hospitalized patients from second- to first-line antibiotic therapy is described.
Through an electronic medical record report, pharmacists identified adult inpatients with penicillin allergy receiving moxifloxacin, intravenous vancomycin, aztreonam, daptomycin, or linezolid, in which a β-lactam antibiotic was preferred. The PASA was administered to identify patients for PST. Skin test negative patients were transitioned to first line β-lactam antibiotic therapy.
Thirty-seven patients consented to the study. Based on the algorithm, 33 patients (89.2%) qualified for PST: 1 patient had a blocked histamine control, 1 was discharged, and 1 withdrew prior to PST. In the 30 patients undergoing PST, historical reactions included anaphylaxis (6 patients, 20%), hives (9, 30%), unknown (5, 16.7%), rash (5, 16.7%), angioedema (4, 13.3%), and shortness of breath (1, 3.3%). Twenty-nine patients (96.7%) were skin test negative and were subsequently transitioned from therapy with aztreonam (5 patients) and/or vancomycin (26 patients) to a β-lactam antibiotic. No patients experienced an adverse reaction, and at least 23 hospital days were avoided, with a cost savings of $50,000.
Our PASA and PST are a safe and cost effective multidisciplinary intervention which facilitated the transition to β-lactam antibiotics. Our approach is unique in that it prioritizes patients based on use of second line antibiotics, and then applies an algorithm to determine eligibility for penicillin skin testing.