Selective Decontamination of the Digestive Tract during Ventilation in the ICU
The SuDDICU Investigators for the Australia and New Zealand Intensive Care Society Clinical Trials Group and the Canadian Critical Care Trials Group
N Engl J Med Published October 29, 2025
DOI: 10.1056/NEJMoa2506398
Abstract
BACKGROUND
Whether selective decontamination of the digestive tract (SDD) reduces mortality among patients undergoing mechanical ventilation and whether it adversely affects microbial ecology in the intensive care unit (ICU) remain unclear. In an earlier analysis of data from Australia, SDD did not result in a lower incidence of in-hospital death than standard care, but data from the full international trial are needed.
METHODS
We randomly assigned ICUs in Australia and Canada to use SDD or to continue standard care for two 12-month periods in patients undergoing mechanical ventilation. Patients in the SDD group received specific oral and gastric antimicrobial interventions for the duration of ventilation and an intravenous antibiotic agent for the first 4 days after enrollment. All other patients in the ICU were included in an observational ecologic assessment. Previously reported data from Australia are now combined with data from Canada. The primary outcome was in-hospital death from any cause at 90 days. The secondary clinical outcomes, assessed at 90 days, were death in the ICU and the number of days alive and free of mechanical ventilation, ICU admission, and hospitalization. Microbiologic secondary outcomes included new positive cultures for bloodstream infections and antibiotic-resistant organisms. For the ecologic assessment, the microbiologic outcomes were tested for noninferiority (noninferiority margin, 2 percentage points).
RESULTS
In this trial involving 20,000 patients in 26 ICUs, 9289 patients were enrolled in the randomized trial and 10,711 were included in the ecologic assessment. At 90 days, 1175 of 4215 patients (27.9%) in the SDD group and 1494 of 5065 (29.5%) in the standard-care group had died before hospital discharge (odds ratio, 0.93; 95% confidence interval [CI], 0.84 to 1.05; P=0.27). New bloodstream infections occurred in 4.9% of the patients in the SDD group and in 6.8% of those in the standard-care group (adjusted mean difference, −1.30 percentage points; 95% CI, −2.55 to −0.05); antibiotic-resistant organisms were cultured in 16.8% and 26.8%, respectively (adjusted mean difference, −9.60 percentage points; 95% CI, −12.40 to −6.80). In the ecologic assessment, noninferiority of SDD was not confirmed for the development of new antibiotic-resistant organisms. Adverse events considered to be related to SDD or standard care were reported in 12 patients (0.3%) in the SDD group and in no patients in the standard-care group. Serious adverse events occurred in 47 patients (1.1%) and 59 patients (1.2%), respectively.
CONCLUSIONS
Among critically ill patients undergoing mechanical ventilation, SDD did not result in a lower incidence of in-hospital death than standard care. (Funded by the National Health and Medical Research Council of Australia and the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT02389036.)
