Colon bacterial flora

Hill MJ, Drasar BS The normal colonic bacterial flora. Gut 1975 16 318—323. 

Hill, M.J., and Drasar, B.S., The normal colonic bacterial flora. Gut, 16 318-323 (1975). Moore, W.E.C., and Holdeman, L.V., Discussion of current bacteriologic investigations of the relationship between intestinal flora, diet and colon cancer. Cancer Res., 35 3418-3420... 

Vargo, D., Doyle, R. and Floch, M.H. 1985. Colonic bacterial flora and serum cholesterol alterations induced by dietary citrus pectin, Am. J. Gastroenterol., 80(5) 361-364. 

The diazoic bond is stable in the gastrointestinal fluids, except in the colonic environment because of the presence of colonic bacterial flora, which produce enzymes able to cleave such bonds. Such polymers can be used to form matrices or coatings that are progressively eroded, allowing localised release of the drug. 

Many studies failed to show any consistent effect of CA on cholesterol absorption[93,95,101]. However, as already mentioned, the feeding of CA alone leads to an increase of both CA and DCA pools. When CA was given together with broad spectrum antibiotics -in order to suppress colonic bacterial flora and so to prevent DCA formation and to achieve a selective expansion of CA pool - a significant increase of cholesterol absorption was observed[98]. 

Colonization and metabolic activity of gastrointestinal bacterial flora do not approach adult values until 2-4 years of age [19]. This has resulted in increased bioavailability of digoxin in infants and young children. 

Besides constipation-related IBS, several studies have also suggested abnormalities of colonic bacterial composition in chronic idiopathic constipation [125]. Here again antibiotic treatment with vancomycin [126, 127], rova-mycin (in combination with diphetarsone, an amebicidal agent) [128,129] or erythromycin [130], which, however, displays a prokinetic activity [131, 132], proved to be capable of reversing long-lasting constipation. Furthermore, the efficacy in both clinical conditions of probiotics [133-135] lends further support to the pathogenic role of bowel flora. 

In a recent study, we found no acquisition of rifaximin resistance in 27 rifaximin-treated subjects colonized by Enterococcus [37]. The MIC50 and MIC90 for the treatment group (rifaximin at a dose of either 400 or 200 mg twice daily for 3 days) were similar (16-64 pg/ml). In two published studies, rifaximin resistance was shown to occur in the bacterial flora of individuals who received treatment with rifaximin at a dose of 800 mg/day for 5 days [9, 27]. Within 1-2 weeks after the end of rifaximin treatment, resistance rates appeared to have decreased to less than 20% of the intestinal flora. The resistant strains detected during treatment appeared to be unstable and unable to persistently colonize the intestinal tract. 

Vergnes D, Moatti N, Monrozies X, Lazorthes F, Enjalbert L Pre-operative colonic preparation using kanamycin and metronidazole Qualitative and quantitative effects on the bacterial flora of the intestine. J Antimicrob Che-mother 1980 6 709-716. 

It is an antisecretory drug. It is 5-ami-nosalicylic acid with linked sulfapyridine through azo bond. The drug is poorly absorbed from the intestine and the azo linkage is broken down by the bacterial flora in the distal ileum and colon to release 5-ami-nosalicylic acid (5-ASA) and sulfapyridine. 5-ASA inhibits locally prostaglandin synthesis, decreases mucosal secretion. It is used in rheumatoid arthritis and ulcerative colitis. Side effects include fever, rashes, blood dyscrasias, nausea, vomiting and headache. 

The absorption of intact quercetin glycosides has been demonstrated by some authors [64,65,76]. Hollmann demonstrated in ileostomy subjects (who lack colon with the bacterial flora, thus circumventing the problem of microbial degradation), that the quercetin glycosides from regular foods (onions, tea) were far better absorbed than pure aglycone (52% vs 24%). 

ASA is taken up by the gastrointestinal tract, particularly in the acetylated form and ehminated as such in the mine. The colon is the predilected place for this acetylation since in the small bowel there is a lack of the responsible bacterial flora. Hence, there is a limited readily absorption of 5-ASA as such in the small bowel. How far this may form a rationale for a possible difference in nephrotoxicity for the different preparations remains to be determined. Indeed, experimental evidence has shown that free 5-ASA is more nephrotoxic than the acetylated form [108,109]. 

Erythromycin estolate in conjunction with rifampin (both drugs administered orally) can be recommended for the treatment of Rhodococcus equi pneumonia in foals. Early diagnosis of the infection and prompt initiation of therapy considerably increase the effectiveness of treatment. Apart from this specific indication, macrolide antibiotics (including erythromycin) and lincosamides (lincomycin and clindamycin) are contra-indicated in horses. Antimicrobial agents in these classes can cause severe disturbance of the balance between commensal bacterial flora in the colon of the horse. 

Colonization and metabolic activity of GI bacterial flora do not approach adult values until ages two to four years (17). This has resulted in increased bioavailability of digoxin in infants and young children (18). The absorption of vitamin K depends, to some extent, on the development of intestinal flora as it synthesizes large amounts of menaquinones, which are potentially available as a source of vitamin K. 

The treatment of D-lactic acidosis consists of oral administration of antibiotics, limitations of oral carbohydrate intake, and recolonization of the colon by bacterial flora which do not produce D-lactate. 

In postmenopausal women with recurrent infections, the lack of estrogen results in changes in the bacterial flora of the vagina, resulting in increased colonization with uropathogenic E. coli. Topically administered estrogen cream is reported to reduce the incidence of infections in this population." ... 

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