Bacterium
Bacteroides fragilis
Anaerobic Gram-negative rod with capsule clue
bak-ter-OY-deez FRAJ-ih-lis
High-yield clue
Anaerobic Gram-negative rod + gut flora + abscess/capsule vocabulary.
Overview
An anaerobic gut-associated rod used to teach abscess vocabulary, capsule virulence concepts, and anaerobe comparison.
Classification
- Gram-negative
- Rod
- Anaerobe
- Gut microbiota member
Lab & identification clues
- Anaerobic growth concept
- Capsule vocabulary
- Bile resistance term in advanced comparisons
Associations
- Intra-abdominal abscess vocabulary
- Normal flora/opportunism contrast
- Metronidazole class association as mechanism vocabulary
Commonly confused with
- Clostridium perfringens
- Enterobacterales
- Fusobacterium vocabulary
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.