Educational resource · Not a medical device · Infectious diseases review in progress · Does not replace clinical judgement

Bacteroides fragilis — Bacteroides

Review by an infectious diseases specialist in progress · edited by a physician, AI-assisted writing · level of evidence computed from the source type · page as of 29 October 2026 · Methodology

Bacteroidaceae · Gram-negative anaerobe

Bactérie anaérobie stricte gram-négatif, 1ère cause d'infection anaérobie. La recherche d'un foyer abdomino-pelvien (péritonite, abcès intra-abdominal, perforation digestive) est décrite comme de principe. L'odeur fétide du pus est évocatrice. Hors du foyer abdomino-pelvien, des abcès cérébraux, hépatiques et pulmonaires sont décrits (Wexler 2007). La résistance au métronidazole est rare mais en augmentation (Wexler 2007).

Scope: dosing as described in the cited guidelines (French or international context, stated by the source), for adults with normal renal function unless stated on the line. No renal or hepatic, paediatric or pregnancy adjustment is provided systematically. These regimens have not been reviewed by any infectious-disease specialist to date.

Documented organ tropism

Organs where foci of Bacteroides fragilis are described in the cited literature. The reported frequency is not an individual probability.

Organ	Tropism	Level of evidence	Sources	Spread route
Colon / Alimentary system	High tropism	Evidence B	3	not recorded
Uterus (abcès tubo-ovarien)	Moderate tropism	Evidence C	1	not recorded
Lung (abcès)	Moderate tropism	Evidence C	1	not recorded
Skin (polymicrobien)	Moderate tropism	Evidence C	1	not recorded

Described portals of entry

• Colon / Alimentary system
• Péritoine

Spread routes recorded: 0 of 4 documented foci A focus without a route is not a focus without spread: the route is simply not recorded.

Associated syndromes

• Bacterial skin infections
• Brain abscess
• Cholecystitis and cholangitis
• Bacterial peritonitis

Sources

• IDSA — Intra-abdominal Infections Guidelines (2010) — doi:10.1086/649554
• Mazuski JE et al. — The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection (Surg Infect) (2017) — doi:10.1089/sur.2016.261
• Wexler HM — Bacteroides: the good, the bad, and the nitty-gritty (2007) — doi:10.1128/CMR.00008-07
• Soper DE — Pelvic inflammatory disease (2010) — doi:10.1097/AOG.0b013e3181e92c54
• Bartlett JG — Anaerobic bacterial infections of the lung and pleural space (Clin Infect Dis) (1993) — doi:10.1093/clinids/16.supplement_4.s248
• Stevens DL & Bryant — Necrotizing Fasciitis (NEJM) (2017) — doi:10.1056/NEJMra1600673

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