Selective digestive decontamination

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.

In a randomized clinical trial among critically ill patients receiving mechanical ventilation, SDD, compared with standard care without STD, 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 the 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.

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