Selective Oral and Digestive Decontamination
Selective oral and digestive decontamination continues to vex quality-improvement advocates. On the one hand, these are amongst the very few prevention strategies in critical care that are not only associated with lower VAP rates but have repeatedly been associated with lower mortality rates in large, rigorous, randomized trials.[72–74] On the other hand, antibiotic stewards continue to worry that widespread use of oral or digestive decontamination will ultimately lead to higher levels of antibiotic resistance that will eventually outweigh the short-term mortality benefit associated with decontamination. Paradoxically, some studies suggest that digestive decontamination may be associated with less net antibiotic use and lower rates of resistant organisms, presumably because decontamination prevents some infections and thus saves some patients from needing treatment courses of antibiotics. And indeed, a few hospitals have reported persistently low rates of antibiotic-resistant organisms sustained for many years after implementing selective digestive decontamination.[76–78] Nonetheless, active surveillance for resistant pathogens amongst all ICU patients (not just those receiving digestive or oral decontamination) does suggest that selective decontamination is associated with small but significant and sustained increases in the unit-wide prevalence of antibiotic-resistant organisms.[79,80]
Most of the large cluster randomized trials of oral and digestive decontamination were conducted in the Netherlands, a country with low prevalence of resistant organisms and low rates of antibiotic utilization compared with many other countries; commentators therefore worry that the effect of digestive decontamination on resistance rates may be magnified in settings with higher baseline rates of resistant pathogens and antibiotic utilization. The most recent European guidelines on the management of HAP and VAP consequently issued a weak recommendation in favor of selective oral decontamination alone, not selective digestive decontamination, and only for settings with low rates of antibiotic-resistant bacteria and low rates of antibiotic consumption.
The recent publication of the R-GNOSIS trial suggests this recommendation was prescient. The R-GNOSIS investigators assessed the impact of oral care with 2% chlorhexidine versus selective oral decontamination versus selective digestive decontamination on ICU-acquired bloodstream infections with resistant organisms and 28-day mortality in a cluster randomized crossover trial amongst 13 European ICUs with moderate to high rates of antibiotic resistance at baseline. They found no differences between arms in either bloodstream infections or 28-day mortality.
Importantly, the selective digestive decontamination arm of the R-GNOSIS trial only included antibiotics administered via a nasogastric tube to the stomach, but not a course of parenteral antibiotics. Some analyses have suggested that a brief course of parenteral antibiotics may be critical to the success of selective digestive decontamination. Thus despite the completion of yet another large, rigorous cluster randomized trial, questions about the role of digestive decontamination in preventing VAP and improving outcomes for ICU patients persist.
Semin Respir Crit Care Med. 2019;40(4):548-557. © 2019 Thieme Medical Publishers