Key facts Bacteria are single cells that can survive on their own, inside or outside the body. Viruses cause infections by entering and multiplying inside the host's healthy cells. It can be difficult to know what causes an infection, because viral and bacterial infections can cause similar symptoms. Antibiotics won't work for viral infections. Misusing antibiotics to treat viral infections contributes to the problem of antibiotic resistance. Antibiotics won't cure viral infections. How are bacteria different from viruses?Bacteria and viruses are too tiny to see with the naked eye. They can cause similar symptoms and are often spread in the same way, but are different in most other ways.Bacteria are single cells that can survive on their own, inside or outside the body. Most bacteria aren't harmful. In fact, you have many harmless and helpful bacteria on your skin and inside your body, especially in the gut to help digest food.Viruses are smaller and are not cells. Unlike bacteria, the...
