S10.2: I thought this was a very important abstract. It concerns small intestinal bacterial overgrowth, which is one of the banes of CF persons' existence. Anyhow, they did not study people; rather they studied CFTR knockout mice--so keep that in mind. CFTR knockout mice has a severe intestinal phenotype and must be fed an elemental liquid diet or treated with oral osmotic laxative to prevent lethal intestinal obstruction. Thy also develop dramatic accumulation of mucus in their intestines, small intestinal bacterial overgrowth (SIBO), inflammation, and failure to thrive. These are similar to humans with CF. Of these changes, this team says, SIBO is of interest because it can be responsible for many of the other aspects of the CF intestinal situation. In the normal intestine, the large intestine is filled with bacteria, with which we live in symbiosis. By contrast, the normal small intestine is relatively sterile. The small intestine has several means to control bacterial load and many of these may be dysfunctional in CF. Mucus sweeps microbes from the small intestine. Poorly cleared intestinal mucus, SIBO, and altered GI motility have all been reported frequently in CF pts. In CFTR knockout mice, Paneth cell innate defenses are impaired, which could add to SIBO. (It should also be mentioned, though the team doesn't mention it, that chronic abx use significantly alters the GI environment.) OK, this team wondered if they could clear mucus accumulation in the CFTR knockout mice's small intestine, whether that would improve overall health. They used a) NAC (a precursor of glutathione: glutathione will do the very same), and b) a polyethylene glycol laxative. The mice fed NAC experienced a 50% reduction in mucus accumulation, and a 63% decrease in SIBO. The laxative reduced mucus accumulation by about 40%, and almost totally eradicated SIBO in the mice, as well as decreased intestinal inflammation and increased body weight gain. This team wonders if altered GI motility is at the root of SIBO, which would explain the expanded results they got from the laxative. They also note that research has shown that particular bacterial species have particular effects on intestinal transit, so they are not sure if the laxative is correcting the bacterial etiology which then alters transit, or if the laxative is altering transit which then alters bacterial species. "An experimental approach that can be used to answer this question is to see if correcting interdigestive transit with prokinetic drugs proves sufficient to reduce mucus accumulation and SIBO in the CF intestine. Prokinetic drugs have shown some benefits in CF pts. Alternatively, administration of PROBIOTIC bacteria to normalize the microbial ecology of the CF intestine may be effective at restoring transit and improving GI health. Probiotic bacteria have been shown to reduce intestinal inflammation in CF pts. Remarkably, in a pilot study, oral probiotic bacteria improved airway function and reduced the occurrence of pulmonary exacerbations in CF children. This result suggests the EXCITING IDEA that immune modulation by probiotic bacteria in the intestine may have systemic effects that benefit CF airway disease as well."