Comparative clinical outcomes of ampicillin/sulbactam versus antipseudomonal broad-spectrum antibiotics for community-onset aspiration pneumonia: a propensity score-matched retrospective cohort study based on guideline-recommended strategies in a secondary care hospital in Japan

Objective

Aspiration pneumonia is highly prevalent among older adults and poses a substantial clinical burden, particularly in aging and rural societies such as Japan. Although the 2024 Japanese Respiratory Society guidelines recommend ampicillin/sulbactam (ABPC/SBT) as first-line therapy, empirical use of antipseudomonal broad-spectrum antibiotics remains common in routine clinical practice. However, evidence supporting the guideline-recommended escalation and de-escalation strategies is limited. Patients and Methods: We conducted a single-center retrospective cohort study of adult patients hospitalized with community-onset aspiration pneumonia between January 2020 and December 2023. Patients received initial empirical therapy with either ABPC/SBT or antipseudomonal broad-spectrum antibiotics (piperacillin/tazobactam or meropenem). The primary outcome was 30-day all-cause mortality. Secondary outcomes included Clostridioides difficile infection (CDI), pneumonia recurrence, length of hospital stay, and duration of antibiotic therapy. Propensity score matching (PSM; up to 1:2) was performed using guideline-based variables, including quick Sequential Organ Failure Assessment score, A-DROP score, and resistant-pathogen risk factors. Subgroup analyses were conducted according to guideline-defined escalation and de-escalation recommendations.