During critical illness the gut does not pass the acid test

The composition and function of intestinal microflora are emerging as integral to both health and disease. During critical illness the normal microbiota are rapidly replaced by pathogenic species as a result of both the physiologic stress itself and the use of antibiotics. In this report, the authors use fecal pH as a surrogate marker to determine the predictive value of the functional output of the intestinal microflora during critical illness. Fecal pH appears to be highly predictive of outcome from critical illness, and may reflect the output of key organic acids such as the short-chain fatty acids, lactic acid, and other important products of the gut microflora.