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Review: Selective decontamination of the digestive tract reduces mortality and some nosocomial infections in critically ill surgical patients

ACP J Club. 1999 Sept-Oct;131:37. doi:10.7326/ACPJC-1999-131-2-037

Source Citation

Nathens AB, Marshall JC. Selective decontamination of the digestive tract in surgical patients. A systematic review of the evidence. Arch Surg. 1999 Feb;134:170-6. [PubMed ID: 99148325]



Does selective decontamination of the digestive tract (SDD) improve clinical outcomes in critically ill surgical and medical patients?

Data sources

English-language studies were identified by searching MEDLINE (1966 to 1996) with the terms decontamination, prophylaxis, intensive care units, and antibiotics. Recent meta-analyses were reviewed, and investigators involved in primary studies were contacted.

Study selection

Studies were selected if they were prospective, randomized, or time series studies evaluating the efficacy of SDD. Studies using historic controls were considered for patient populations for which available evidence was limited.

Data extraction

Data were extracted on randomization, blinding, analysis, patient selection, similarity of groups at baseline, extent of follow-up, treatment protocol, co-interventions, and number of patients who received an intervention other than that to which they were allocated. Outcomes of interest were death, nosocomial infections (pneumonia, bacteremia, urinary tract infection, and wound infection), and length of intensive care unit (ICU) stay.

Main results

The search identified 11 trials of surgical ICU patients (trials with ≥ 75% of patients admitted after trauma or major surgery) and 10 trials of medical ICU patients (trials with < 25% of patients admitted after trauma or major surgery). Among surgical patients, SDD reduced overall mortality; nosocomial pneumonia, bacteremia, and urinary tract infections (Table); and length of ICU stay (8 studies, 15.2 d for SDD vs 16.9 d for control, P < 0.05) but did not reduce nosocomial wound infections. Among medical patients, SDD reduced nosocomial pneumonia and urinary tract infections but not mortality, nosocomial bacteremia (Table), or length of ICU stay.


Among critically ill surgical patients, selective decontamination of the digestive tract reduces mortality, nosocomial pneumonia, bacteremia, urinary tract infections, and length of ICU stay. Among critically ill medical patients, it reduces nosocomial pneumonia and urinary tract infections.

Source of funding: No external funding.

For correspondence: Dr. J.C. Marshall, The Toronto Hospital, EN 9-234, 200 Elizabeth Street, Toronto, ON M5G 2C4, Canada. FAX 416-595-9486.

Table. Efficacy of selective decontamination of the digestive tract in surgical and medical intensive care unit patients

Outcomes Odds ratio (95% CI)
Surgical patients Medical patients
Death 0.70 (0.52 to 0.93) 0.91 (0.71 to 1.18)
Pneumonia 0.19 (0.15 to 0.26) 0.45 (0.33 to 0.62)
Bacteremia 0.51 (0.34 to 0.75) 0.77 (0.43 to 1.36)*
Urinary tract infection 0.51 (0.34 to 0.76) 0.51 (0.32 to 0.82)

*Not significant.


SDD is a strategy aimed at reducing the contribution of gut flora to infectious complications in patients who are seriously ill. Randomized trials and several meta-analyses have clearly shown that SDD decreases the incidence of pneumonia. Although few individual trials have shown an effect on survival, the most recent meta-analysis by the SDD Trialists Collaborative Group showed a clinically important and statistically significant reduction in mortality (1).

Surgical ICU patients treated with SDD had a 30% lower mortality risk than control patients, whereas medical ICU patients derived no such benefit. The apparent beneficial effect of SDD in surgical ICU patients may reflect a higher risk for as-piration pneumonia related to anesthesia, surgical manipulation, trauma, or prolonged gut dysfunction. Given the 30% attributable mortality rate of pneumonia in ICU patients (2), an effective pneumonia prevention strategy may confer some mortality advantage.

This meta-analysis should stimulate a reexamination of SDD in selected patient groups. Uncertainty exists about which surgical patients are most likely to benefit, the long-term emergence of resistant organisms, conflicts with current prophylactic and perioperative antibiotic regimens, and unevaluated costs. The results provide justification for large trials of SDD incorporating systemic-only treatment arms and microbiologic surveillance in well-defined surgical patient subsets, particularly those at high risk for pneumonia.

Nicholas Nissen, MD
Derek C. Angus, MD, MPHUniversity of Pittsburgh School of MedicinePittsburgh, Pennsylvania, USA


1. Selective Decontamination of the Digestive Tract Trialists' Collaborative Group. Meta-analysis of randomised controlled trials of selective decontamination of the digestive tract. BMJ. 1993;307:525-32.

2. Heyland DK, Cook DJ, Griffith L, Keenan SP, Brun-Buisson C, for the Canadian Critical Care Trials Group. The attributable morbidity and mortality of ventilator-associated pneumonia in the critically ill patient. Am J Respir Crit Care Med. 1999;159:1249-56.