Bacteroides fragilis is a topic covered in the Johns Hopkins Antibiotic (ABX) Guide.

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  • Small, pleomorphic Gram negative anaerobic bacillus. B. fragilis causes most human Bacteroides infections.
  • Other members of B. fragilis group include:
    • Bacteroides distasonis
    • Bacteroides ovatus
    • Bacteroides thetaiotaomicron
    • Bacteroides vulgatus
  • Easily grown relative to other anaerobes.
  • Colonizes virtually all human colons.
  • Organism possibly important in gut for immune modulation.
  • B. fragilis group almost always susceptible to metronidazole, carbapenems, beta-lactam/beta-lactamase inhibitors and chloramphenicol.

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Last updated: January 30, 2016