Using samples from a multi-center, observational study of adults with CF, we identified 7 bacterial species for which fecal relative abundances decreased significantly with ETI, a highly effective CFTR modulator, and that directly correlated with a fecal measure of inflammation, calprotectin, supporting a strong pathophysiologic relationship between CFTR function, intestinal inflammation, and microbiota. This evidence concerns the gene CFTR and cystic fibrosis.