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Selective Digestive Tract or Oropharyngeal Decontamination and ICU Outcomes
Abstract & Commentary
By David J. Pierson, MD, Editor, Professor, Pulmonary and Critical Care Medicine, Harborview Medical Center, University of Washington, Seattle, is Editor for Critical Care Alert.
Synopsis: This large multicenter study in 13 Dutch ICUs found that regimens of both systemic and limited oropharyngeal decontamination were associated with significant reductions in 28-day mortality when compared with standard care, although the differences were apparent only after adjustment for covariants and the overall prevalence of antibiotic-resistant organisms in the participating institutions was very low.
Source: de Smet AM, et al. Decontamination of the digestive tract and oropharynx in ICU patients. N Engl J Med 2009;360:20-31.
The effects of selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD; SDD without systemic antibiotics), which are measures for preventing ICU-acquired infections, on patient outcomes and microbial resistance patterns remain unsettled and controversial. This study, carried out in 13 ICUs in the Netherlands in 2004-2006, sought to determine the effects of SDD and SOD on 28-day mortality in comparison with standard therapy. A cluster-randomization, crossover design was used, in which all patients in a given ICU received the same study regimen during a fixed interval, with all 3 regimens being used in each unit in random order with intervening washout periods. Patients admitted to the ICU whose physicians expected them to require more than 48 hours of mechanical ventilation or to remain in the ICU for at least 72 hours were included.
SDD consisted of 4 days of intravenous cefotaxime plus the topical application of a mixture of tobramycin, colistin, and amphotericin B to the oropharynx and stomach. SOD consisted of the same regimen minus the intravenous cefotaxime. When patients were receiving SDD or SOD, other antimicrobial use was discouraged. Surveillance cultures of endotracheal aspirates and oropharyngeal and rectal swabs were obtained on admission and twice weekly. In the standard care group, no routine surveillance cultures were obtained, and there were no restrictions on antimicrobial use by the patients' physicians.
During the 27-month study period, 5939 patients were enrolled, with 2045 receiving SDD, 1904 SOD, and 1990 standard care. This represented 89% of all eligible patients admitted to the study ICUs during that time. Overall 28-day mortality was 27%. Compared to the mortality rate of 27.5% in the standard care group, that in the SOD group was 2.9% lower at 26.9% (relative reduction, 11%; number needed to treat, 34), and that in the SDD group was slightly lower at 26.6% (3.5% absolute reduction; 13% relative reduction; number needed to treat, 29). With model adjustment for age, sex, APACHE II score, intubation status, and other factors, the odds ratio for death in the first 28 days after ICU admission was 0.86 (95% confidence interval [CI], 0.74-0.99) in the SOD group, and 0.83 (95% CI, 0.72-0.97) in the SDD group, as compared to that for patients in the standard care group.
ICU-acquired bacteremia due to Staphylococcus aureus, non-lactose-fermenting gram-negative rods, and Enterobacteriaceae was significantly reduced in patients receiving either SOD or SDD. No instances of methicillin-resistant S. aureus (MRSA) were documented in the 5939 study patients. Clostridium difficile was detected in 15 patients (0.8%) in the standard care group, in 5 (0.3%) in the SOD group, and in 9 (0.4%) in the SDD group. For all 3 groups, the rate of antibiotic resistance in bacterial cultures was less than 5%; these rates tended to be lower in the SOD and SDD groups than in the standard care group.
Despite a number of (mainly European) studies concluding that SDD or SOD reduces the incidence of hospital-acquired infections and improves certain patient outcomes, this therapy has not been recommended in current widely used guidelines,1 and has not been widely adopted in American ICUs. This new study, while large in scope and carefully conducted, seems unlikely to change this situation despite its significantly better outcomes with SDD or SOD as compared with standard care. One reason I am hesitant to recommend SDD or SOD for ICU patients in this country is the uncertain generalizability of this study's results with respect to antimicrobial resistance. The low incidence of antimicrobial resistance in surveillance cultures, the very low incidence of C. difficile, and the complete absence of MRSA, are in striking contrast to what is found in most North American ICUs. One would expect that the higher the prevalence of these things in the unit, the less likely SDD or SOD would reduce infection rates and improve patient outcomes; in such circumstances, the likelihood of increased rates of resistance would also be a concern.
Debate will likely continue about the potential value of SDD and/or SOD in reducing ventilator-associated pneumonia and other ICU-acquired infections. This study fuels this debate but does not convince me that this intervention should be adopted in my ICU.