What’s the difference between bacterial and viral infections? Their causes. One is caused by bacteria, the other by viruses. This matters when choosing the right treatment. For example, antibiotics only kill bacteria, not viruses. So they can’t help you beat the common cold. When you’re feeling sick, it’s tough to know what kind of infection you have. That’s when your primary care provider (PCP) can help. They test and diagnose your sickness to make sure you have the most effective treatment. Le