The threat of SDD is to lead the selection and overgrowth of antibiotic resistant microorganisms. In a recent study from the Netherlands, where the incidence of MRSA and vancomycin resistant enterococcus (VRE) are very low, a reduction in the frequency of colonization with resistant gram-negative bacteria and no effect on the acquisition of MRSA were reported (138) . But the studies from the ICUs where MRSA was endemic, increased incidence of MRSA was reported (139, 140) . Therefore, in ICUs with high incidence of multi-resistant microorganisms, SDD cannot be used. On the other hand, in trauma and surgical patients, SDD seems more effective than in medical patients, may be due to less colonisation [141] . In conclusion the routine use of SDD in ICUs is not recommended, it should be decided according to the patient population studied and the characteristic of ICU.