Selective decontamination of the digestive tract: all questions answered?

Although many studies have shown beneficial effects of SDD on the incidence of respiratory tract infections, SDD did not become routine practice because mortality reduction was not demonstrated in individual trials, beneficial effects on duration of ventilation, ICU stay or hospital stay were not demonstrated, cost-efficacy had not been demonstrated, and selection of antibiotic resistance was considered a serious side-effect. A recent study has now shown improved patient survival and lower prevalence of antibiotic resistance in patients receiving SDD. Why could this study show mortality reduction, where all others studies had failed before? And do the microbiological data unequivocally prove protective effects of SDD on emergence of antibiotic resistance? Interestingly, the reported mortality reductions exceeds even the most optimistic predictions from previous meta-analyses, but a clear explanation is not yet evident. The data on antibiotic resistance, however, are rather superficial and do not allow to interpret the underlying epidemiological dynamics. Therefore, the recent findings are provocative and shed new light on the SDD issue, warranting studies confirming its beneficial effects but also addressing several important aspects related to study design.