Key Points
- Selective decontamination of the digestive tract (SDD) is a preventive infection control strategy involving the application of topical nonabsorbable antibiotics to the oropharynx and upper gastrointestinal tract (e.g., stomach), usually combined with a short course of intravenous antibiotics in mechanically ventilated intensive care unit (ICU) patients.
- It is often compared with selective oral decontamination, which excludes gastric and systemic antimicrobials.
- The principal aim of SDD is to prevent mortality from ventilator-associated pneumonia or bacteremia caused by pathogenic bacteria and secondary overgrowth with yeasts from the upper gastrointestinal tract.
- The level of Evidence is moderate, and antimicrobial resistance is a concern. SDD is recommended only in ICU settings with a low prevalence of antibiotic resistance.1
Background
- The framework emerged in the 1980s, initially applied to immunocompromised hematological disease patients and trauma patients.2
- The intervention is aimed at preventing ventilator-associated pneumonia, and is based on the principle of colonization resistance, whereby the indigenous intestinal anaerobic flora provides protective effects against secondary colonization with aerobic gram-negative bacteria.3
- The target is commonly pathogenic microorganisms, such as the following:
- Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis, Escherichia coli, Candida albicans, Klebsiella, Proteus, Morganella, Enterobacter, Citrobacter, Serratia, Acinetobacter, and Pseudomonas species.4
- Nonabsorbable antimicrobial agents are used, as well as a short course of IV antibiotic to prevent early infections.
Treatment Population and Common Protocols
- The Infectious Disease Society of America 2022 guidelines recommend considering SDD only in ICU settings with a low prevalence of antibiotic resistance.1
- SDD is recognized as an “additional approach,” rather than “essential practice.”
- SDD is standard care in the Netherlands but used sporadically in other settings.5
- A sample protocol is below2:
- Initiate SDD as soon as possible in mechanically ventilated patients.
- Oral paste (colistin 10 mg, tobramycin 10 mg, nystatin 125,000 IU) is applied to the buccal mucosa and oropharynx every 6 hours.
- Gastric suspension (colistin 100 mg, tobramycin 80 mg, nystatin 2×10^6 IU) is administered via gastric/post pyloric tube every 6 hours.
- A four-day course of intravenous (IV) antibiotic (third-generation cephalosporin or ciprofloxacin) is administered, unless the patient is already receiving antibiotics with gram-negative coverage.
- Continue topical components for the duration of mechanical ventilation via endotracheal tube or until day 90.
- The institution must maintain a protocol for surveillance cultures for resistant organisms.
Level of Evidence
- A 2022 meta-analysis of ~24,000 subjects reported a pooled risk ratio for mortality of 0.91 (95% credible interval, 0.82-0.99)6, indicating a modest mortality benefit.
- SDD was associated with reduced risk of ventilator-associated pneumonia (RR 0.44, 95% CrI 0.36-0.54) and ICU-acquired bacteremia (RR 0.68, 95% CrI 0.57-0.81).
- Notably, mortality benefit was observed only in trials that included an IV agent.
- There are limited studies of effects within settings with high rates of antimicrobial resistance.4
- Outbreaks of extended-spectrum β-lactamase-producing bacteria and colistin/aminoglycoside-resistant Enterobacteriaceae during SDD have been reported.7
Table 1. Notable findings from important publications on selective decontamination of the digestive tract
Abbreviations: SOD, selective oral decontamination; SDD, selective decontamination of the digestive tract; RCT, randomized controlled trials; ICU, intensive care unit; IV, intravenous
Concerns
- SDD implementation requires a standardized protocol that includes dosing schedules, application techniques, and surveillance culture timing.
- The generalizability of SDD remains controversial because many positive studies originate from Northern Europe, where low baseline antimicrobial resistance and strong stewardship practices are common.
- Potential ecological effects on the gastrointestinal system remain an area of active investigation.
- There is potential for adverse drug reactions, and concern for toxicity if agents, such as tobramycin, are absorbed systemically.
References
- Klompas M, Branson R, Cawcutt K, et al. Strategies to prevent ventilator-associated pneumonia, ventilator-associated events, and nonventilator hospital-acquired pneumonia in acute-care hospitals: 2022 update. Infect Control Hosp Epidemiol. 2022;43(6):687-713. PubMed
- Myburgh JA, Seppelt IM, Goodman F, et al. Effect of selective decontamination of the digestive tract on hospital mortality in critically ill patients receiving mechanical ventilation: a randomized clinical trial. JAMA. 2022;328(19):1911-21. PubMed
- Wittekamp BH, Plantinga NL, Cooper BS, et al. Decontamination strategies and bloodstream infections with antibiotic-resistant microorganisms in ventilated patients: a randomized clinical trial. JAMA. 2018;320(20):2087-98. PubMed
- Cavalcanti AB, Lisboa T, Gales AC. Is selective digestive decontamination useful for critically ill patients? Shock.2017;47(1 Suppl 1):52-7. Link
- Wittekamp BHJ, Oostdijk EAN, Cuthbertson BH, Brun-Buisson C, Bonten MJM. Selective decontamination of the digestive tract (SDD) in critically ill patients: a narrative review. Intensive Care Med. 2020;4 (2):343-9. PubMed
- Hammond NE, Myburgh J, Seppelt I, et al. Association between selective decontamination of the digestive tract and in-hospital mortality in intensive care unit patients receiving mechanical ventilation: a systematic review and meta-analysis. JAMA. 2022;328(19):1922-34. PubMed
- Oostdijk EAN, Kesecioglu J, Schultz MJ, et al. Effects of decontamination of the oropharynx and intestinal tract on antibiotic resistance in ICUs: a randomized clinical trial. JAMA. 2014;312(14):1429-37. PubMed
- de Smet AMGA, Kluytmans JAJW, Cooper BS, et al. Selective digestive tract decontamination and selective oropharyngeal decontamination and antibiotic resistance in patients in intensive-care units: an open-label, clustered group-randomised, crossover study. Lancet Infect Dis. 2011;11(5):372-80. PubMed
- Daneman N, Sarwar S, Fowler RA, Cuthbertson BH. Effect of selective decontamination on antimicrobial resistance in intensive care units: a systematic review and meta-analysis. Lancet Infect Dis. 2013;13(4):328-41. PubMed
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