Bacteria that do not need oxygen to survive are called anaerobic bacteria. They may also live in places that have very little oxygen. A couple examples of diseases that are caused by anaerobic bacteria are tetanus and botulism.
These bacteria live in the mouth, gastrointestinal tract, and on the skin. They can also live in the ears and sinuses as well as several other places on and in the human body.
Some people are at risk for becoming very sick due to anaerobic bacteria. These are people who have had recent surgery and have blood vessel disease.