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Bacteroides fragilis: Wikis


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From Wikipedia, the free encyclopedia

Scientific classification
Kingdom: Bacteria
Phylum: Bacteroidetes
Class: Bacteroidetes
Order: Bacteroidales
Family: Bacteroidaceae
Genus: Bacteroides
Species: fragilis
Bacteroides fragilis
Classification and external resources
MeSH D001442

Bacteroides fragilis is a pleomorphic Gram negative bacillus and an obligate anaerobe of the gut[1].


Clinical signifiance

It is involved in 90% of anaerobic peritoneal infections.

Bacteroides fragilis acts primarily at the surface of the mucosa.[2]



In general, B. fragilis is susceptible to metronidazole, carbapenems, beta-lactam/beta-lactamase inhibitor combinations (e.g., Unasyn, Zosyn), and certain antimicrobials of the cephamycin class, including cefoxitin. The bacteria have inherent high-level resistance to penicillin. Clindamycin is no longer recommended as the first-line agent for B. fragilis due to emerging high-level resistance (>30% in some reports).[3]

Other use

Bacteriophages infecting B. fragilis are commonly used as tracers of human faecal material; see work undertaken by the University of Barcelona and EPHRU (Environment and Public Health Research Unit) at the University of Brighton[4].

Polysaccharide A (PSA) from this bacteria is reported to be involved in the protection of experimental colitis induced by Helicobacter hepaticus.[5] Further research into B. Fragilis PSA has shown that it intermediates in several markers of a healthy mammalian immune system: the levels of CD4 T cells, the balance of T-helper cytokines, the presence of well-defined follicular structures in the spleen, and in the inflammatory gut response to pathogens. [6][7][8]


  1. ^
  2. ^ Kuwahara T, Yamashita A, Hirakawa H, et al. (October 2004). "Genomic analysis of Bacteroides fragilis reveals extensive DNA inversions regulating cell surface adaptation". Proc. Natl. Acad. Sci. U.S.A. 101 (41): 14919–24. doi:10.1073/pnas.0404172101. PMID 15466707. PMC 522005.  
  3. ^ Mandell GL, Bennett JE, Dolin R (2004). Principles and Practice of Infectious Diseases (6th ed. ed.). Churchill Livingstone. ISBN 0443066434.  
  4. ^
  5. ^ A microbial symbiosis factor prevents intestinal inflammatory disease
  6. ^ S.K. Mazmanian, The Scientist, Volume 23, Issue 8, Page 34. "The Microbial Health Factor: Just one molecule can make the difference in mediating a healthy immune response. Surprisingly, it comes from bacteria"
  7. ^ S.K. Mazmanian et al., "An immunomodulatory molecule of symbiotic bacteria directs maturation of the host immune system," Cell, 122:107–18, 2005.
  8. ^ S.K. Mazmanian et al., “A microbial symbiosis factor prevents intestinal inflammatory disease,” Nature, 453:620-25, 2008.


Up to date as of January 23, 2010

From Wikispecies


Main Page
Superregnum: Bacteria
Regnum: Bacteria
Phylum: Bacteroidetes
Classis: Bacteroidetes
Ordo: Bacteroidales
Familia: Bacteroidaceae
Genus: Bacteroides
Species: Bacteroides fragilis
Strain: Bacteroides fragilis NCTC 9343 - Bacteroides fragilis YCH46 - Bacteroides fragilis 3_1_12 -



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