Occur as: a result of contamination of otherwise sterile sites such as the bronchial tree by aspiration of oral anaerobes, peritonitis and abdominal abscess from bowel perforation, osteomyelitis after oral surgery and some episodes of pelvic inflammatory disease or infections of tissue with compromised vascular supply such as diabetic foot infections with impaired circulation and poor oxygenization, infection of pressure sores with fecal anaerobic flora in vascular damaged tissue.
Frequently have multiple organisms.
Often organisms capable of anaerobic and aerobic growth coexist with anaerobes.
Can involve all body systems and sites, with most infections in the abdomen, pelvis, respiratory tract, skin and soft tissues.
Difficult to isolate from infectious sites and are often overlooked secondary to their fastidious nature.
Some anaerobes produce toxins such as Clostridium, which can produce food poisoning, botulism, tetanus or soft tissue inflammation.
Suggested by foul odor, the presence of gas and the finding of gram positive and gram negative flora on Gram stain of purulent material with little or no growth on aerobic cultures.
Many organisms sensitive to penicillin with the exception of Bacteroides fragilis and Clostridium difficile.
Generally infections by anaerobes originating above the diaphragm are frequently sensitive to penicillin, whereas infections from below the diaphragm are resistant to Bacteroides fragilis.
Associated with thrombotic diseases.
5-12% of septic anaerobic infections associated with thrombophlebitis.