PSHP 2026 Residency Conference

Purpose: To evaluate the likelihood of receiving guideline-concordant antimicrobial therapy among patients with S. pneumoniae bacteremia or pneumonia with and without a documented β-lactam allergy.
Methods: This retrospective cohort study included adults admitted to 3 academic medical centers in a single health system from January 2021 to May 2025 with S. pneumoniae bacteremia or pneumonia. Patients were identified via positive blood or respiratory cultures and included if ≥ 18 years old and received systemic antimicrobials. Exclusions were polymicrobial infections or infectious complications including empyema, endocarditis, bone/joint, or CNS. Patients were stratified by documented β-lactam allergy at admission (1:3 allergy to non-allergy). Data was collected using REDCap™. Patients were treated in accordance with institutional Antimicrobial Guidelines, ensuring therapy aligned with established recommendations. The primary outcome was the receipt of guideline-directed therapy, which was analyzed using the chi-square test. Secondary outcomes were summarized descriptively, and statistical significance was defined as a p-value<0.05.
Results: Of 64 patients, 16 (25%) had a documented β-lactam allergy. Guideline-concordant therapy was received by 12 (75.0%) with an allergy and 26 (54.2%) without. Patients with documented β-lactam allergy were more likely to receive guideline-directed therapy, but this difference was not statistically significant (χ² = 1.38, p = 0.24). Among cases of non-concordant therapy, the most common reason in patients with β-lactam allergy was prolonged duration (54.5%), switching to an oral fluoroquinolone (36.4%) and inappropriate oral therapy (9.1%). In patients without