MICROBIOLOGY

• Small, pleomorphic Gram-negative anaerobic bacillus.
  • Of all species, B. fragilis causes most human Bacteroides infections.
• Other commonly encountered members of the B. fragilis group [BFG] include Bacteroides, Parabacteroides and Phocaeicola species: speciation has been aided by the employment of MALDI-TOF[3].
  • Bacteroides distasonis, Bacteroides merdae, and Bacteroides goldsteinii have been reclassified to a new genus, Parabacteroides.
    • Tannerellaceae” family has been proposed as a new name.
      • Therefore, the revised taxonomy are Parabacteroides distasonis, P. merdae, and P. goldsteinii
  • Bacteroides ovatus
  • Bacteroides thetaiotaomicron
  • Bacteroides uniformis
  • Bacteroides vulgatus
• Quickly grown relative to other anaerobes.
• Bacteroides spp. colonize all human colons, representing ~ 25% of human intestinal microbiota.
  • BFG are outnumbered 10-100x by other Bacteroides spp.
• Organisms are possibly important in the gut for immune modulation.