Anaerobes

• May be Gram-positive or negative, bacilli or cocci (see table below).

• Many anaerobes are commensal organisms of the mouth, oropharynx, gastro-intestinal tract and female genital tract .

• Infections with anaerobes are frequently polymicrobial – other aerobic bacteria or facultative anaerobes (eg: E coli) are often present.

• Often associated with foul or putrid odour.

• May be associated with necrotic tissue.

Main clinical Infections:

• Skin and soft tissue infections e.g. leg ulcers, pressure sores, human or animal bites, traumatic or surgical wounds:

• Deep abscesses or collections of pus e.g. brain abscess, psoas abscess.

• Intra-abdominal infections, including biliary sepsis

• Dental infections.

• Bacteraemia.

Usually sensitive to:

• Metronidazole (except Actinomyces spp.)

• Co-amoxiclav

• Meropenem / Imipenem

• Clindamycin

• Piperacillin/tazobactam  

• Penicillins (except Bacteroides spp.)

In many infections caused by anaerobes the most important aspect of treatment is surgical e.g. drainage of abscess, debridement of necrotic tissue, as well as treatment of other co-pathogens.

Page last edited: 22/05/2009

Caution; the antibiotic doses recommended on this website are intended for adult patients with normal renal and liver function unless otherwise stated. Dosing advice for patients with renal impairment is available here.

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