Background: It is unclear whether antibiotics impact delirium outcomes in older adults with pyuria or bacteriuria in the absence of systemic signs of infection or genitourinary symptoms.

Methods: We registered our systematic review protocol with PROSPERO (CRD42023418091). We searched the Medline and Embase databases from inception until April 2023 for studies investigating the impact of antimicrobial treatment on the duration and severity of delirium in older adults (≥60 years) with pyuria (white blood cells detected on urinalysis or dipstick) or bacteriuria (bacteria growing on urine culture) and without systemic signs of infection (temperature > 37.9C [>100.2F] or 1.5C [2.4F] increase above baseline temperature, and/or hemodynamic instability) or genitourinary symptoms (acute dysuria or new/worsening urinary symptoms). Two reviewers independently screened search results, abstracted data, and appraised the risk of bias. Full-text randomized controlled trials (RCTs) and observational study designs were included without restriction on study language, duration, or year of publication.

Results: We screened 984 citations and included 4 studies comprising 652 older adults (mean age was 84.6 years and 63.5% were women). The four studies were published between 1996 and 2022, and included one RCT, two prospective observational cohort studies, and one retrospective chart review. None of the four studies demonstrated a significant effect of antibiotics on delirium outcomes, with two studies reported a worsening of outcomes among adults who received antibiotics. The three observational studies included had a moderate or serious overall risk of bias, while the one RCT had a high overall risk of bias.

Conclusions: Our systematic review found no evidence that treatment with antibiotics is associated with improved delirium outcomes in older adults with pyuria or bacteriuria and without systemic signs of infection or genitourinary symptoms. Overall, the evidence was limited, largely observational, and had substantial risk of bias.