Let's take a closer look at the microbes which make us ill. Bacteria Bacteria are very simple single celled organisms. There are millions of them in the soil, water and the air. They can be found living on their own or in groups. To see bacteria we would need to use a microscope.
Bacteria can multiply very quickly.
Here is typical bacterial cell. We think of fungi, such as mushrooms and mould, growing on bread. Fungi can also grow in and on the body. Athlete's foot and ringworm are both skin complaints caused by fungi. Viruses Viruses are one of the most interesting group of organisms we study.