Condition predisposing to<unk> s include: exposure of a sterile body location to a high inoculum of indigenous bacteria of mucous membrane flora origin, inadequate blood supply and tissue necrosis which lower the oxidation and reduction potential which support the growth of anaerobes. Conditions which can lower the blood supply and can predispose to<unk>  are: trauma, foreign body, malignancy, surgery, edema, shock, colitis and vascular disease. Other predisposing conditions include splenectomy, neutropenia, immunosuppression, hypogammaglobinemia, leukemia, collagen vascular disease and cytotoxic drugs and diabetes mellitus. A preexisting<unk>  caused by aerobic or facultative organisms can alter the local tissue conditions and make them more favorable for the growth of anaerobes. Impairment in defense mechanisms due to<unk>  conditions can also favor<unk> . These include production of leukotoxins (by Fusobacterium spp.), phagocytosis intracellular killing impairments (often caused by encapsulated anaerobes) and by succinic acid ( produced by Bacteroides spp.), chemotaxis inhibition (by Fusobacterium, Prevotella and Porphyromonas spp.), and proteases degradation of serum proteins (by Bacteroides spp.) and production of leukotoxins (by Fusobacterium spp.). The hallmarks of<unk>  include suppuration, establishment of an abscess, thrombophlebitis and gangrenous destruction of tissue with gas generation.<unk>  bacteria are very commonly recovered in chronic<unk> s, and are often found following the failure of therapy with antimicrobials that are ineffective against them, such as trimethoprim–sulfamethoxazole (co-trimoxazole), aminoglycosides, and the earlier quinolones. Some<unk> s are more likely to be caused by<unk>  bacteria, and they should be suspected in most instances. These<unk> s include brain abscess, oral or dental<unk> s, human or animal bites, aspiration pneumonia and lung abscesses, amnionitis, endometritis, septic abortions, tubo-ovarian abscess, peritonitis and abdominal abscesses following viscus perforation, abscesses in and around the oral and rectal areas, pus-forming necrotizing<unk> s of soft tissue or muscle and postsurgical<unk> s that emerge following procedures on the oral or gastrointestinal tract or female pelvic area. Some solid malignant tumors, ( colonic, uterine and bronchogenic, and head and neck necrotic tumors, are more likely to become secondarily infected with anaerobes. The lack of oxygen within the tumor that are proximal to the endogenous adjacent mucosal flora can predispose such<unk> s.
Anaerobic infection
Fungal infection
Odontogenic infection
Protozoan infection
Antibiotic synergy
Electrolyte exclusion effect
Opportunistic infection
Viral disease