The study investigated the effectiveness of selective gastrointestinal decontamination (SDD) in mechanically ventilated patients in intensive care units. The study involved 9289 patients from 26 intensive care units in Australia and Canada. Patients in the SDD group received oral and non-gastric antibiotics during ventilation and intravenous antibiotics during the first 4 days of hospitalization. At 90 days, 27.9% of patients in the SDD group and 29.5% in the standard care group had died, indicating no statistically significant difference in mortality. Patients with SDD had fewer new bloodstream infections (4.9% vs. 6.8% in the standard care group). There were also fewer cases of colonization with resistant bacteria in the SDD group (16.8% versus 26.8%). Adverse events associated with SDD were very rare (0.3% of patients). The study did not confirm the non-inferiority of SDD in relation to the emergence of new resistant organisms.