Impact of Gut Decontamination Strategies on the Clinical, Microbiological, and Ecological Outcomes of Critically Ill Patients Requiring Mechanical Ventilation:A Systematic Review and Meta-analysis

Objective<br/>To determine the impact of gut decontamination strategies (selective decontamination of the digestive tract and selective oral decontamination) on patient-level clinical and microbiological outcomes and unit-level ecological outcomes in critically ill patients requiring mechanical ventilation.<br/><br/>Data Source<br/>We searched MEDLINE, EMBASE, Cochrane Library, and trial registries from inception to October 7, 2025.<br/><br/>Study Selection<br/>We included randomized controlled trials (RCTs) evaluating gut decontamination<br/>compared to standard and cohort studies reporting ecological surveillance data in intensive care units (ICU) implementing gut decontamination.<br/><br/>Data Extraction<br/>We extracted data on study and patient characteristics, gut decontamination regimens, patient outcomes (e.g., mortality), patient-level microbiology outcomes (e.g., ventilatorassociated pneumonia [VAP], bloodstream infections, antimicrobial resistance), and unit-level ecological outcomes (e.g., antimicrobial resistance).<br/><br/>Data Synthesis<br/>We identified 39 RCTs (n = 37,449) and 24 cohort studies (n &gt;383,159). Overall, gut<br/>decontamination strategies probably reduce hospital mortality (relative risk [RR] 0.92, 95% confidence interval [CI] 0.86 to 0.97, moderate certainty), with regimens including intravenous antibiotics driving the mortality benefit compared to topical-only regimens. Gut decontamination strategies reduce bloodstream infections (RR 0.68, 95% CI 0.57 to 0.80, high certainty), mechanical ventilation duration (mean difference [MD] -0.91 days, 95% CI -1.23 to - 0.58, high certainty) and probably reduce VAP (RR 0.44, 95% CI 0.36 to 0.54, moderate certainty) and therapeutic antibiotic administration (RR 0.63, 95% CI 0.49 to 0.82, moderate certainty). Gut decontamination strategies may not increase patient-level antibiotic-resistant organisms nor Clostridioides difficile infection<br/>(low certainty). Moreover, ecological surveillance data suggest that gut<br/>decontamination strategies may, at the unit-level, reduce VAP without increasing<br/>antibiotic-resistant organisms (low certainty).<br/><br/>Conclusion<br/>Gut decontamination strategies reduce hospital mortality, the duration of mechanical ventilation, VAP, bloodstream infections, and therapeutic antibiotic administration (moderate to high certainty). Importantly, gut decontamination strategies may not increase antimicrobial resistance at the patient or ICU level (low certainty).