Prolonged intravenous (IV) antibiotics are standard for brain abscess management but prolong hospital stays and increase costs. Intravenous-to-oral switch (IVOS) has been proposed as a safe alternative. This systematic review aimed to assess the effectiveness of IVOS strategies and compare clinical outcomes according to duration of IV exposure prior to oral switch. A systematic review and meta-analysis was conducted according to PRISMA guidelines. Five electronic databases were searched (PubMed, Embase, Scopus, Web of Science, and Cochrane Library) up to May 11, 2025. Eligible studies included retrospective or prospective cohort studies in patients aged ≥ 16 years with brain abscess, reporting at least one predefined clinical outcome. Studies were excluded if they did not evaluate oral antibiotic therapy or did not report extractable outcome data. Outcomes assessed included treatment success (primary), recurrence, adverse events, and hospital stay. Risk of bias was evaluated using the ROBINS-I V2 tool. Exposure thresholds for IV duration were retained as defined within each individual study, given the absence of a uniform protocol across cohorts. Five retrospective cohort studies comprising 488 patients were included; four provided sufficient data for meta-analysis. Median time to oral switch ranged from 9 to 19 days (reported in three studies). Overall treatment success was 70.2% (321/457), with 83.2% (154/185) in shorter IV exposure groups and 61.4% (167/272) in longer IV exposure groups (study defined). In pooled analysis, shorter IV exposure (study-defined thresholds) was associated with higher treatment success compared with longer IV exposure (OR 2.69; 95% CI 1.66–4.37; p < 0.001; I 2 = 0%); however, exposure thresholds and outcome definitions varied across studies, and the pooled estimate reflects a directional association rather than the effect of a standardized intervention. Sensitivity analysis confirmed robustness, and funnel plot inspection revealed no major publication bias, though this assessment was limited by the small study number. IVOS strategies appear to be a safe and potentially effective approach for selected patients with brain abscess, potentially reducing hospitalization without compromising outcomes. Evidence remains limited by retrospective design and moderate-to-serious risk of bias. Prospective trials are warranted. The review was prospectively registered in PROSPERO (CRD420251060028).
Jimenez et al. (Sat,) studied this question.
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