II. Pathophysiology
- Bacteroides fragilis are obligate anaerobic Gram Negative Rods in the Bacteroidaceae family
- Bacteroides fragilis has a capsule
- Bacteroides fragilis secretes an Enterotoxin (BFT)
- However, does not contain Lipid A or Endotoxin (unlike most other Gram Negative Bacteria)
- Bacteroides fragilis is a normal colonizer of the Gastrointestinal Tract (25% of intestinal flora)
- Low virulence unless intestinal wall is perforated
- May also be associated with Inflammatory Bowel Disease flares
III. Associated Conditions
- Bacteroides fragilis rarely colonizes the mouth (uncommon cause of Aspiration Pneumonia)
- Intraabdominal anaerobic Bacterial Infections and abscesses
- Bacteroides fragilis is found in most intraabdominal anaerobic infections
- Among the most commonly isolated Bacteria in anaerobic bacteremia
- Occurs with Bowel perforation, Mesenteric Ischemia, Pelvic Inflammatory Disease, Septic Abortion
- Wound Infections
IV. Management
- Source control with abscess drainage
- Antibiotics with highest efficacy against Bacteroides fragilis (lower resistance rates)
- Antibiotics with high Bacteroides fragilis resistance rates (low susceptibility)
V. Prognosis
- Bacteroides fragilis bacteremia is associated with mortality as high as 30%
VI. Resources
- lsaghir (2023) Bacteroides fragilis, StatPearls, Treasure Island, Fl
VII. References
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| Definition (NCI_CDISC) | Any bacterial organism that can be assigned to the species Bacteroides fragilis. |
| Definition (NCI) | A species of obligately anaerobic, Gram-negative, rod shaped bacteria assigned to the phylum Bacteroidetes. This species is nonmotile, non-spore forming, indole positive, produces hydrogen sulfide, does not reduce nitrate, hydrolyzes esculin and starch, does not ferment trehalose, melezitose or arabinose, and is penicillin resistant. B. fragilis is commensal and part of the normal human gastrointestinal tract flora, but may become pathogenic in other body regions. |
| Definition (MSH) | Gram-negative bacteria occurring in the lower intestinal tracts of man and other animals. It is the most common species of anaerobic bacteria isolated from human soft tissue infections. |
| Concepts | Bacterium (T007) |
| MSH | D001441 |
| SnomedCT | 55247009 |
| LNC | LP16785-5 |
| Swedish | Bacteroides fragilis |
| Czech | Bacteroides fragilis |
| English | Bacteroides fragilis, Bacillus fragilis Veillon and Zuber 1898, Bacteroides fragilis (Veillon and Zuber 1898) Castellani and Chalmers 1919, bacillus fragilis, bacteroides fragilis, Bacillus fragilis, Bacteroides inaequalis, Bacteroides incommunis, Bacteroides uncatus, Fusiformis fragilis, Pseudobacterium fragilis, Pseudobacterium inaequalis, Pseudobacterium incommunis, Pseudobacterium uncatum, Ristella fragilis, Ristella incommunis, Ristella uncata, Sphaerophorus inaequalis, Sphaerophorus intermedius, BACTEROIDES FRAGILIS, Bacteroides fragilis ss. fragilis, Bacteroides fragilis (organism) |
| Finnish | Bacteroides fragilis |
| Russian | BAKTEROIDY LOMKIE, BACTEROIDES FRAGILIS, БАКТЕРОИДЫ ЛОМКИЕ |
| Polish | Bacteroides fragilis |
| Norwegian | Bacteroides fragilis |
| Spanish | Bacteroides fragilis (organismo), Bacteroides fragilis, subespecie fragilis, Bacteroides fragilis |
| French | Bacteroides fragilis, Ristella fragilis |
| German | Bacteroides fragilis |
| Italian | Bacteroides fragilis |
| Dutch | Bacteroides fragilis |
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