Non-Antibiotic Approaches to Infection that Preserve the Microbiome in Critically Ill Patients

In critically ill patients, the gut microbiota is subjected to various factors including antimicrobial exposure, modified gastrointestinal transit, nutrition support, as well as infection, which may lead to dysbiosis during the intensive care unit and hospital stay. Dysbiosis occupies an increasingly important role in driving morbidity and perhaps mortality in the critically ill or injured. Given that antibiotics lead to dysbiosis, it is relevant to understand the range of non-antibiotic approaches to infection-including those related to multi-drug-resistant organisms-that may leave the microbiome unimpacted. These strategies most prominently include the elimination of unabsorbed antibiotic agents from the digestive tract, pro-/pre-/synbiotics, fecal microbiota transplant, selective digestive and oropharyngeal decontamination, phage therapy, anti-sense oligonucleotides, structurally nanoengineered antimicrobial peptide polymers, and vitamin C-based lipid nanoparticles for adoptive macrophage transfer. Herein, we review the rationale for these therapies, current data regarding their use in critically ill patients, and the therapeutic potential for strategies that are not yet deployed in human medical care.