Bacteria are made up of just one cell
Bacteria are single-cell organisms. Some need oxygen to survive and others do not. Some love the heat, while others prefer a cold environment. Well-known examples of include salmonella and staphylococcus .
Most aren't dangerous for humans. Many of them even live on or in our body and help us to stay healthy. For instance, lactic acid in the bowel help us to digest food. Other help the by fighting germs. Some are also needed in order to produce certain types of food, like yogurt, sauerkraut or cheese.
Less than 1% of all are responsible for diseases – but this is just a rough estimate because there are no exact numbers. Tuberculosis, for instance, is caused by . Bacterial infections can be treated with antibiotics. These are medicines that kill the or at least stop them from multiplying.
Many other infections – including diarrhea, colds or tonsillitis – can also be caused by , but viruses are usually responsible for them. Antibiotics aren't effective against viruses. So it's not a good idea to start using them too soon if it's only suspected that are causing the .