What are obligate anaerobes?

Obligate anaerobes are that must live in an environment devoid of oxygen. Oxygen is toxic to obligate anaerobes and will kill them.
An example of an obligate anaerobe is Clostridium tetani , which causes tetanus. Clostridium tetani form spores that allow them to lie dormant in unfavorable environments. If a person receives a puncture wound in which C. tetani spores are present, the bacteria will be able to become active due to the fact that a deep wound with dead cells will form an anaerobic environment. C. tetani produces two toxins, and can cause death.