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
Frequently asked questions
What is Bacteroides fragilis?
An anaerobic gut-associated rod used to teach abscess vocabulary, capsule virulence concepts, and anaerobe comparison.
What is the Gram stain of Bacteroides fragilis?
Bacteroides fragilis is Gram negative.
What are the lab clues for Bacteroides fragilis?
Lab clues for Bacteroides fragilis include Anaerobic growth concept, Capsule vocabulary, and Bile resistance term in advanced comparisons.
What is Bacteroides fragilis commonly confused with?
Bacteroides fragilis is commonly confused with Clostridium perfringens, Enterobacterales, and Fusobacterium vocabulary.
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.