Effects of Selective Digestive Decontamination (SDD) and Selective Oropharyngeal Decontamination (SOD) in ICU Patients

• Introduction to Infections in ICU:
  • Infections acquired in the intensive care unit (ICU) often occur during the treatment of critically ill patients, increasing morbidity, mortality, and healthcare costs.
  • Prophylactic antibiotic regimens such as selective decontamination of the digestive tract (SDD) and selective oropharyngeal decontamination (SOD) can reduce the incidence of nosocomial infections and mortality in ICU patients.
• SDD Approach:
  • The SDD approach involves prevention of secondary colonization with gram-negative bacteria, Staphylococcus aureus, and yeasts through nonabsorbable antimicrobial agents in the oropharynx and gastrointestinal tract.
  • It also includes preemptive treatment of possible infections caused by commensal respiratory tract bacteria through systemic administration of cephalosporins during the patient’s first 4 days in the ICU.
• Background of SDD Approach:
  • The intestinal flora, primarily consisting of anaerobic bacteria, is considered an important defense mechanism against intestinal colonization by potentially pathogenic microorganisms.
  • Disruption of anaerobic flora by antibiotics may create a portal of entry for pathogenic microorganisms.
• From Concept to Practice in the ICU:
  • Earlier experiences with SDD in leukemia patients suggested the potential for preventing infections in ICU patients.
  • The establishment of SDD regimen in ICU involved the application of nonabsorbable antimicrobial agents in the oropharynx and gastrointestinal tract, and preemptive treatment of infections through systemic administration of cephalosporins.
• Clinical Results:
  • Conflicting results of clinical trials led to insufficient scientific evidence to recommend SDD as a routine infection control measure in ICU patients.
  • SDD showed promising outcomes in prophylactic strategies for major gastrointestinal surgery and postoperative infections.
• Randomized ICU Studies:
  • A Dutch single-center study reported significantly lower ICU and hospital mortality rates, shorter length of stay, and lower incidence of antibiotic resistance in patients receiving SDD.
  • Subsequent multicenter study compared SDD with SOD and showed reduction in mortality rates in both groups.
• Meta-analyses:
  • Various meta-analyses reported overall positive effects of SDD and SOD in reducing mortality and the incidence of respiratory tract infections (RTIs).
  • An individual patient data meta-analysis found significantly lower hospital mortality during SDD and SOD compared to control.
• Conclusion on SDD:
  • SDD demonstrated favorable effects in reducing mortality and incidence of infections, although some studies had limitations.
  • Overall, SDD showed potential in reducing nosocomial infections and mortality in ICU patients.
• Trial Design and Setting:
  • Cluster randomized trial in 13 European, non-Dutch or Scandinavian ICUs with moderate to high levels of antibiotic resistance
  • Used SDD, SOD, or a chlorhexidine mouthwash for 6-month periods
• Patient Inclusion:
  • ICUs with at least 5% prevalence of extended-spectrum beta-lactamase among Enterobacteriaceae-causing bloodstream infections were eligible
  • Total of 8665 patients included
• Study Outcomes:
  • No significant differences found in the incidence of ICU-acquired bacteremias with multidrug-resistant, gram-negative bacteria and for mortality at day 28 between the three groups
  • Positive effects on respiratory tract colonization and infection with lower incidence of ICU-acquired bacteremia with Enterobacteriaceae compared to SOD
• Microbiologic Effects:
  • SDD showed a decrease in colonization rates with gram-negative bacteria and eradication of cephalosporin-resistant Enterobacteriaceae
  • SDD and SOD led to a lower incidence of certain bacteremias compared to controls
• Antibiotic Resistance:
  • Contrary to suggestions, overall decrease in antibiotic-resistant, gram-negative microorganisms during SDD
  • No increase observed in incidence rates of ICU-acquired antibiotic-resistant bacteria over a 21-year period with SDD
• Impact on MRSA and VRE:
  • Use of topical antibiotics for SDD or SOD considered contraindicated in settings where MRSA and VRE are highly prevalent
  • SDD associated with less acquisition and more eradication of cephalosporin- and carbapenem-resistant bacteria
• Conclusion:
  • No large RCTs performed in countries with higher levels of antibiotic resistance until this trial
  • Overall, SDD showed positive effects on antibiotic resistance and clinical outcomes
• Effects on Bacterial Colonization and Infection Rates:
  • Shift towards gram-positive organisms detected after introduction of SDD in trauma patients, leading to an outbreak and increased carriage rates with MRSA.
  • SDD with topical vancomycin associated with improved patient outcome and lower colonization rates with MRSA in a Spanish burn unit.
• Ecological Effects of SDD and SOD:
  • SDD and SOD have marked ecologic effects, with resistance levels decreasing during interventions and increasing after discontinuation.
  • Evidence from a 4-year ecologic study supports the positive effects of SOD and SDD on antibiotic resistance in individual patients, suggesting a herd effect.
• Effectiveness in Specific Patient Groups:
  • Meta-analysis suggests increased SDD efficacy in surgical patients, with lower rates of surgical site infections and anastomotic leakage in patients undergoing gastrointestinal surgery.
• Hospital-Acquired Infections after SOD and SDD:
  • No significant increase in the overall infection rate after discontinuation of SOD and SDD post-ICU, refuting the hypothesis that discontinuation affects clinical outcomes.
  • Low rates of HAI and overall low mortality rates post-ICU contradict the idea that discontinuation of SDD and SOD increases infection rates.