Selective digestive decontamination (SDD) is a process used on intensive care units to reduce the occurrence of infections in critically ill people.
It was originally described for immunocompromised patients with hematologic disease and in patients with trauma and was extended to critically ill patients treated in ICUs.
Selective decontamination of the digestive tract is the application of topical nonabsorbable antibiotics and antifungal agents to the upper G.I. tract combined with a short course of intravenous antibiotics in patients receiving mechanical ventilation via an endotracheal tube.
It involves the administration of antibiotics to reduce bacteria and fungi in the digestive tract to prevent them from causing illness in those at high risk.
Many ICU acquired infections, in particular infections of the respiratory tract, are caused by gram-negative bacteria, staphylococcus aureus, and yeast usually resulting from colonization of the upper and lower digestive tracts – mouth, stomach, and intestines.
SDD aims to reduce the incidence of ICU acquired infections by eradicating and preventing colonization of the digestive tract with the previously mentioned microorganisms.
SDD involves application of topical, nonabsorbable antimicrobial agents: Colistin, tobramycin and nystatin that selectively spare the anaerobic flora.
Patients also it receive intravenous antibiotics, usually a second or third generation cephalosporin to treat respiratory tract infections that may be incubating at the time of ICU admission.
It can target both normal and abnormal flora.
The aim of SDD is to prevent the development of ventilator associated pneumonia caused by pathogenic gram-negative bacteria and secondary overgrowth with yeast from the upper G.I. tract.
SDD usually consists of an oral paste and gastric suspension of three non-absorbed antimicrobial agents compared with a short course of an intravenous antibiotic with an appropriate antimicrobial spectrum.
SDD consists of daily antibiotic prophylaxis with an anaerobic sparing, oropharyngeal paste (colistin, tobramycin, and nystatin) a gastric slurry (a mixture of similar antibiotic agents), and typically four days of treatment with intravenous ceftriaxone, cefotaxime or ciprofloxacin.
The regimen is designed to reduce oral gastrointestinal burden of organisms and the risks of pneumonia, resulting from aspiration and the bacteria, resulting from bacterial translocation across the gut wall.
In a randomized clinical trial among critically ill patients receiving mechanical ventilation, SDD, compared with standard care without SDD, did not significantly reduce in hospital mortality (28% vs 29.1%, respectively) (SUDDICU investigators).
An analysis of 32 randomized clinical trials including 24,389 participants of adult patients in the ICU treated with mechanical ventilation, the use of SDD compared with standard care placebo was associated with a lower mortality: The pool estimated risk ratio for the mortality for STD compared with standard care was is 0.91% (Hammond N).
The cumulative evidence from clinical SDD studies and meta-analysis suggest evidence that STD improves patient outcomes and there is a low prevalence of antibiotic resistance.
In a randomized trial, SuDDICU: The use of SDD is compared with standard care had no significant effect on the incidence of in hospital death, nor did it appear to alter the number of days alive and free from mechanical ventilation, but was associated with fewer bloodstream infections than standard care, fewer antibiotic resistant organisms than standard care, no apparent differences in the total defined daily doses of antibiotics or in the development of new Clostridia difficile infections, it was non-inferior to standard care with regard to the development of new bloodstream and C. difficile infections, there was no apparent differences in antibiotic resistant infections, but appeared to have of a lower mortality than standard care in patients with acute brain injury.