Prebiotic Fiber in the ICU

This study will test prebiotic fiber in 20 adults who are receiving broad-spectrum
antibiotics in the medical or surgical ICU by open-label randomization of patients to
approximately 20 g prebiotic fiber/day including 45% short-chain fructooligosaccharides
versus 0 g fiber/day by providing one of two feeds. Per 10 ounces of feed, both the high and
low fiber feeds contain identical micronutrients and have 296 kilocalorie (kCal), 19 g
protein, 8 g fat, and 39 g carbohydrates. The sole difference is that the fiber-containing
feed has 4 g fiber including 45% short-chain fructooligosaccharides per 10 ounces whereas the
other feed has 0 g fiber. Randomization will take place at the time the order for enteral
feeding is placed. Rather than supplying the feed itself, the investigators will supply a
randomized recommendation for a feed type (i.e., high vs low fiber) and the feed will be
obtained from the hospital pharmacy in the usual manner. Determination of the feed rate and
duration will be decided on the individual patient's needs by the treating ICU team. The
primary outcome will be to determine whether high fiber feeds alter the gut microbiome in the
face of antibiotics and critical illness, calculated by comparing within-individual
microbiome differences from baseline to Day 3 in each intervention group.

Inclusion Criteria:

- Medical or surgical ICU patients ≥18 years old at our institution;

- Receiving broad-spectrum antibiotics at the time of enrollment;

- Deemed appropriate for the study by the treating ICU team;

- With capacity to give consent or have an appropriate surrogate;

- Able to undergo assessment within 4 hours of the order for enteral feeds;

- Expected to receive enteral feeds for ≥3 days but not yet receiving them.

Exclusion Criteria:

- Inability to receive enteral feeds;

- Celiac disease or known allergy to fiber;

- Surgery involving the intestinal lumen within 30 days;

- Limited treatment goals (i.e., do-not-resuscitate (DNR), do-not-intubate (DNI), or no
escalation of care);

- Lack of capacity to consent and lack of an appropriate legally authorized
representative.