Bacteria

Bacteria are tiny unicellular organisms found throughout nature which can only be seen with a microscope. They live in the soil and in and on all plants and animals. Some are useful to the human body -- such as the bacteria which digest food in the intestines. Others live in and on the body without causing harm. Some, however, invade the tissues and cause dangerous and even life threatening infections. Bacteria are treated with antibiotics. However, certain antibiotics only kill certain bacteria.