Metronidazole
M. Lindsay Grayson, Sara E. Cosgrove, Suzanne M. Crowe, M. Lindsay Grayson, William Hope, James S. McCarthy, John Mills, Johan W. Mouton, David L. Paterson in Kucers’ The Use of Antibiotics, 2017
Of the anaerobic bacteria, Bacteroides spp. are important clinically because they are the organisms most commonly isolated from patients with suppurative anaerobic infections and they have the broadest spectra of recognized resistances to antimicrobial agents (Rasmussen et al., 1997; Aldridge et al., 2003). The Bacteroides fragilis group has undergone considerable taxonomic changes, with more than 20 species now specified, but includes Bacteroides fragilis, Parabacteroides distasonis, B. thethaiotaomicron, B. vulgatus, and B. ovatus (Brook et al., 2013). Bacteremia caused by an organism of the B. fragilis group of organisms has been shown to be an independent risk factor for mortality (Redondo et al., 1995).
Immune Response to Microbial Toxins in Inflammatory and Neurodegenerative Disorders
David Perlmutter in The Microbiome and the Brain, 2019
Recent studies point to the role of abnormal microbiota, the release of particular LPS, and bacterial CDT as plausible mechanisms that could contribute to the pathogenesis of various autoimmune diseases [Vatanen et al. 2016]. A population-based microbiome study identified specific bacterial compounds, the absence or presence of which were associated with health status and disease [Vatanen et al. 2016]. The study followed the gut microbiome development of 222 infants in Northern Europe from birth until the age of three. Early-onset autoimmune diseases are common in Finland and Estonia, but less prevalent in Russia. One explanation for this disparity may have been found in the microbiome of the study participants. Researchers detected an abundance of Bacteroides species in the gut microbiomes of Finnish and Estonian children, while the Russian children showed a predominance of E. coli. It seems that Bacteroides LPS inhibits innate immune signaling and endotoxin tolerance, rendering immune response less effective. This study supports a model through which exposure to different subtypes of LPS produced by gut microbiota, particularly the LPS that is produced by the Enterobacter genus, can contribute to the development of intestinal inflammatory diseases and autoimmunities that affect sites distal to the gut such as lupus and arthritis [Kim et al. 2016; Rosser and Mauri 2016].
Indicators of microbial quality *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Bacteroidesspp. (order Bacteriodales) are gram-negative, rod shaped bacteria that are the most abundant bacteria in human feces, outnumbering E. coliand Enterococcus (Madigan et al. 2003). Bacteroides are facultative anaerobic, meaning they can tolerate oxygen but prefer and will only thrive in anaerobic environments. Consequently, re-growth of Bacteroides in the environment is limited (Kreader,1998). Although detection of anaerobic bacteria to assess fecal contamination has traditionally been avoided due to difficulty associated with cultivating anaerobic bacteria, modern molecular methods including the polymerase chain reaction (PCR/qPCR) now make detection of these organisms practical in most laboratories with molecular biology capabilities (Bernhard and Field 2000). One study of swimming-associated illness showed a positive association with Bacteriodales but not with Bacteroides (Wade et al. 2010). The primary advantage of using Bacteroides is its usefulness in microbial source tracking: BacteroidesHF183 has been shown to be highly specific to humans (Boehm et al. 2013).
Gut Bacteroides species in health and disease
Published in Gut Microbes, 2021
Metabolites secreted by different Bacteroides spp. assist in maintaining stability of the immune system. These species are primary producers of short-chain fatty acids in the human gut, mostly in the form of acetate and propionate. These are important for the maintenance of intestinal homeostasis.171 Both acetate and propionate are potent anti-inflammatory mediators as they inhibit the release of pro-inflammatory cytokines from neutrophils and macrophages.172 Cruz-Bravo et al. described an anti-cancerous role of propionate which induced apoptosis in human colon carcinoma cells.173 Also, butyrate increases expression of tight-junction proteins in the gut to reduce potential gut hyperpermeability. This, in turn, decreases inflammation and endotoxemia that are associated with leaky gut.174 In the human gut, Bacteroides spp. are the principal synthesizers of Vitamin K, which is mainly produced by members of the human gut bacteriome.175 It may prevent or treat osteoporosis by increasing the bone mineral density.176
Enterobacteriaceae and Bacteroidaceae provide resistance to travel-associated intestinal colonization by multi-drug resistant Escherichia coli
Published in Gut Microbes, 2022
Matthew Davies, Gianluca Galazzo, Jarne M. van Hattem, Maris S. Arcilla, Damian C. Melles, Menno D. de Jong, Constance Schultsz, Petra Wolffs, Alan McNally, Willem van Schaik, John Penders
Various Bacteroides species exhibit immunomodulatory effects that are beneficial to the host and can increase the colonization resistance to invading bacteria. A major mechanism of this is the inhibition of host inflammation via the secretion of sphingolipids,31 a signaling molecule or outer-member vesicles containing polysaccharide A,32 a molecule that induces the production of T cells to suppress inflammation.33 Low-grade intestinal inflammation perturbs the gut microbiome and can enhance the colonization of E. coli,34 so reducing this is vital to maintain colonization resistance to invading bacteria. Bacteroides species may have further immunomodulatory effects via the improvement of host macrophage’s phagocytic function35 or via an increased xylan degradation,36 which has links to an enhanced immune system and improved health.37,38 Moreover, Bacteroides species can produce a variety of short-chain fatty acids and organic acids, including acetic acid, propionic acid, isovaleric acid and succinic acid. Short-chain fatty acids have been shown to provide colonization resistance against antibiotic-resistant Enterobacteriaceae, among others, by triggering intracellular acidification.39 To reveal a potential protective role of metabolites, including sphingolipids, xylan breakdown products and short-chain fatty acids, produced by Bacteroides species or other members of the microbiome, future studies on the fecal metabolome are warranted.
Microbial enterotypes beyond genus level: Bacteroides species as a predictive biomarker for weight change upon controlled intervention with arabinoxylan oligosaccharides in overweight subjects
Published in Gut Microbes, 2020
Lars Christensen, Claudia V. Sørensen, Frederikke U. Wøhlk, Louise Kjølbæk, Arne Astrup, Yolanda Sanz, Mads F. Hjorth, Alfonso Benítez-Páez
In four recent post-hoc analyses of studies conducted in Denmark, we have linked Prevotella abundance in the human gut microbiota to weight loss, when consuming whole grain and fiber-rich diet ad libitum.9–12 Specifically, the whole-grain fiber, arabinoxylan, is largely consumed as these are highly abundant in rye bread, a staple food item among Danish participants.13 On the other hand, Bacteroides is commonly associated with a “Western diet” low in fiber, and high in fat and refined sugars. However, the remarkable glycolytic potential of some Bacteroides species hinders the complete association of such microbes with fat-enriched diets and adiposity in humans.14,15 In our previous analyses, these subjects dominated by Bacteroides species have little weight control success when consuming diets rich in fiber and whole grain.9–12
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