Many anaerobic bacteria are normal flora in sites of the body that have low oxygen levels. The anaerobic flora cause disease (abscesses or peritonitis) when they are introduced into sterile sites or when the balance of organisms is upset and pathogenic anaerobes predominate (Clostridium difficile colitis with antibiotic treatment). Environmental anaerobes also cause disease (tetanus, botulism, and gas gangrene).
Types
anaerobic bacteria abscesses
clostridial infections