Bacteria can make you sick it can even kill you If there would be no bad bacteria then the earth would be perfect and everyone would be happy. They can spread the germs They can give you the flu and they can spread from country or state to state they can also give you food poisoning one thing that you can get from bad bacteria is wringworm.
They can kill you and make you turn different colors they can make more of them inside you dosen't that sound gross but hey its true they attach themselves and make you sick I would not want to have a bacteria in me it could even be really painful That is some of the ways that bacteria can be harmful

This is what they look like