Gastrointestinal microflora

The penicillins as natural and semisynthetic agents are used primarily against susceptible Pasteurella sp., staphylococci, streptococci, clostridia, and CoTynebacterium sp. Penicillin is widely used for therapeutic purposes against these organisms and in animal feeds as a growth promoter. The latter effect is considered to be a result of subtie and reversible effects on the gastrointestinal microflora. 

The gastrointestinal microflora provide another potential site for drug metabolism within the GIT, and it has received some attention. In normal subjects the stomach and proximal small intestine contain small numbers of microorganisms. Concentrations of these organisms increase toward the distal end of the intestine. A wide variety of aerobic and anaerobic organisms are present in the gut. The microflora, derived primarily... 

Newman K. (1994). Mannan-oligosaccharides Natural polymers with significant impact on the gastrointestinal microflora and immune system , in Lyon, T.P. Biotechnology in the Feed Industry, Nottingham University Press, Nicolasville, Kentucky, 167-180. 

Blood donors with selective IgA deficiency have a normal gastrointestinal microflora without evidence of bacterial overgrowth [191]. In patients with complex immunodeficiency increased bacterial colonization is seen in... 

Savage DC Gastrointestinal microflora in mammalian nutrition. Annu Rev Nutr 1986,6 155-178. 

The relative contribution of the enzymatic and nonenzymatic reactions is frequently examined but seldom reported explicitly in in vitro studies, and is all but impossible to assess in in vivo investigations. Another factor complicating the interpretation of in vivo results is the contribution of gastrointestinal microflora, whose hydrolytic capacity is particularly marked and varied... 

Apart from glucuronic acid and sulfate conjugation of hydroxycoumarins, other phase II pathways of coumarin metabolism have been identified. For example, ortho-coumaric acid may be conjugated with glycine (Lake, 1999), and a coumarin mercapturic acid conjugate has also been reported (Huwer et al., 1991). Coumarin may also be metabolized by the gastrointestinal microflora to 3,4-dihydrocoumarin and ort/io-hydroxyphenylpropionic acid under anaerobic conditions (Scheline, 1968). 

Another concern in the food safety arena is consumers who may prefer consuming raw or undercooked foods, despite the risks known to them. Although consumers need to be educated about avoiding such foods it is very difficult to change customs and cultures of a population and it may be more effective to consider other more cost-effective interventions (Molins, Motarjemi, and Kaferstein, 2001). However, increased public scrutiny about the use of antibiotics and other additives in the animal feed industry has now directed research toward alternative means for manipulating gastrointestinal microflora in livestock (Castillo et al., 2004). 

Reprinted from International Journal of Pharmaceutics, Vol. 97 M. A. Shamat The role of the gastrointestinal microflora in the ... 

Berg, R.D., The indigenous gastrointestinal microflora, Trends Microbiol, 4,430 35, 1996. 

Variable rates of colonisation of gastrointestinal microflora and beta-glucuronidase activity may also add to the variation and unpredictability of oral drug absorption in neonates and young infants. 

The main probiotic preparations available on the market are known as Lactic Acid Bacteria (LAB), for the most part represented by lactobacilli and bifidobacteria, which are important constituents, normally present, of the gastrointestinal microflora, and that produce lactic acid as a major metabolite. Moreover, also certain yeasts and bacilli are counted among probiotics. Table 37.3 reports the microorganisms recognized as probiotics and used in the production of functional foods. 

J. H. Carter, M. A. McLafferty, P. Goldman (1980) Role of the gastrointestinal microflora in amygdalin (laetrile)-induced cyanide toxicity. Biochem. Pharmacol, 29, 301-304. 

A prebiotic is defined as a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health. ... 

Besides the detoxifying role played by gut bacteria towards mycotoxins and other xenobiotics, the maintenance of a correct balance in the gastrointestinal microflora is crucial for proper nutrient uptake and for an efficient protection against pathogens, according to the so-called "intestinal homeostasis." Thus an impaired balance of the intestinal microbiome, such as in a dysbiosis condition, could adversely affect human health (Figure 8.3). 

Arabinogalactan biodegrades through fermentation in the gastrointestinal microflora of the human body. Hepatic clearance follows first-order kinetics, whereas the highest concentration of arabinogalactan is found in the liver rapidly after injection [120]. 

The competitive exclusion concept was originated by Nurmi and Rantala (1973), based on the study of Salmonella in chickens. Newly hatched birds in modern hatcheries are not able to obtain the normal gut flora of adult birds. As a result, the intestines of chicks can be easily colonized by foodbome pathogens when present. When the chickens were inoculated immediately after birth with the intestinal content of a Salmonella-free adult bird, the frequency of Salmonella infections was radically reduced and the number of Salmonella needed to colonize the ceca of chicks increased. Hence, the normal gastrointestinal microflora of adult chickens can competitively exclude Salmonella from colonizing the naive intestinal tract of chicks. 

Guggenbuhl, P., A. Seon, A. Pifl6n Quintana and C. Simoes Nunes, 2007. Effects of dietary supplementation with benzoic acid (VevoVitall ) on the zooteohnical performance, the gastrointestinal microflora and the ileal digestibility of the young pig. Livest. Sci. 108, 218-221. 

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