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Bacteroides
Bacteroides spp. anaerobically cultured in blood agar medium.
Scientific classification
Kingdom: Bacteria
Phylum: Bacteroidetes
Class: Bacteroidetes
Order: Bacteroidales
Family: Bacteroidaceae
Genus: Bacteroides
Castellani & Chalmers 1919
Species

B. acidifaciens
B. distasonis (reclassified as Parabacteroides distasonis)
B. gracilis
B. fragilis
B. oris
B. ovatus
B. putredinis
B. pyogenes
B. stercoris
B. suis
B. tectus
B. thetaiotaomicron
B. vulgatus
etc.

Bacteroides is a genus of Gram-negative, bacillus bacteria. Bacteroides species are non-endospore-forming, anaerobes, and may be either motile or non-motile, depending on the species.[1] The DNA base composition is 40-48% GC. Unusual in bacterial organisms, Bacteroides membranes contain sphingolipids. They also contain meso-diaminopimelic acid in their peptidoglycan layer.

Bacteroides are normally mutualistic, making up the most substantial portion of the mammalian gastrointestinal flora,[2] where they play a fundamental role in processing of complex molecules to simpler ones in the host intestine.[3][4][5] As many as 1010-1011 cells per gram of human feces have been reported.[6] They can use simple sugars when available, but the main source of energy is polysaccharides from plant sources.

One of the most important clinically is Bacteroides fragilis.

"Bacteroides melaninogenicus" has recently been reclassified and split into Prevotella melaninogenica and Prevotella intermedia. [7]

Contents

Pathogenesis

Bacteroides species also benefit their host by excluding potential pathogens from colonizing the gut. Some species (B. fragilis, for example) are opportunistic human pathogens, causing infections of the peritoneal cavity, gastrointestinal surgery, and appendicitis via abscess formation, inhibiting phagocytosis, and inactivating beta-lactam antibiotics.[8] Although Bacteroides species are anaerobic, they are aerotolerant and thus can survive in the abdominal cavity.

In general, Bacteroides are resistant to a wide variety of antibiotics — β-lactams, aminoglycosides, and recently many species have acquired resistance to erythromycin and tetracycline. This high level of antibiotic resistance has prompted concerns that Bacteroides species may become a reservoir for resistance in other, more highly-pathogenic bacterial strains.[9] [10]

References

  1. ^ Madigan M, Martinko J (editors). (2005). Brock Biology of Microorganisms (11th ed.). Prentice Hall. ISBN 0-13-144329-1.  
  2. ^ Dorland WAN (editor) (2003). Dorland's Illustrated Medical Dictionary (30th ed.). W.B. Saunders. ISBN 0-7216-0146-4.  
  3. ^ Wexler, H. M. (Oct 2007). "Bacteroides: the good, the bad, and the nitty-gritty" (Free full text). Clinical microbiology reviews 20 (4): 593–621. doi:10.1128/CMR.00008-07. ISSN 0893-8512. PMID 17934076. PMC 2176045. http://cmr.asm.org/cgi/pmidlookup?view=long&pmid=17934076.   edit
  4. ^ Xu, J.; Gordon, I. (Sep 2003). "Inaugural Article: Honor thy symbionts" (Free full text). Proceedings of the National Academy of Sciences of the United States of America 100 (18): 10452–10459. doi:10.1073/pnas.1734063100. ISSN 0027-8424. PMID 12923294. PMC 193582. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=12923294.   edit
  5. ^ Xu, J.; Mahowald, A.; Ley, E.; Lozupone, A.; Hamady, M.; Martens, C.; Henrissat, B.; Coutinho, M. et al. (Jul 2007). "Evolution of symbiotic bacteria in the distal human intestine" (Free full text). PLoS biology 5 (7): e156. doi:10.1371/journal.pbio.0050156. ISSN 1544-9173. PMID 17579514. PMC 1892571. http://dx.plos.org/10.1371/journal.pbio.0050156.   edit
  6. ^ Finegold SM, Sutter VL, Mathisen GE (1983). Normal indigenous intestinal flora (pp. 3-31) in Human intestinal microflora in health and disease.. Academic Press. ISBN 0-12-341280-3.  
  7. ^ "Bacteroides Infection: Overview - eMedicine". http://emedicine.medscape.com/article/233339-overview. Retrieved 2008-12-11.  
  8. ^ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9.  
  9. ^ Salyers AA, Gupta A, Wang Y (2004). "Human intestinal bacteria as reservoirs for antibiotic resistance genes". Trends Microbiol 12 (9): 412–6. doi:10.1016/j.tim.2004.07.004. PMID 15337162.  
  10. ^ Löfmark, S.; Jernberg, C.; Jansson, K.; Edlund, C. (Dec 2006). "Clindamycin-induced enrichment and long-term persistence of resistant Bacteroides spp. And resistance genes" (Free full text). The Journal of antimicrobial chemotherapy 58 (6): 1160–1167. doi:10.1093/jac/dkl420. ISSN 0305-7453. PMID 17046967. http://jac.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=17046967.   edit

See also

External links

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Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Superregnum: Bacteria
Regnum: Bacteria
Phylum: Bacteroidetes
Classis: Bacteroidetes
Ordo: Bacteroidales
Familia: Bacteroidaceae
Genus: Bacteroides
Species: Bacteroides fragilis - Bacteroides thetaiotaomicron - Bacteroides vulgatus -


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