What germs can cause cold sores and fever blisters in the mouth and throat?

Several: Some bacterial infections can cause sores in the mouth. Viral infections such as herpes, coxsackie, or epstein-barr can do the same. It is important to distinguish between the two as the treatment for each is different. Generally viral infections in otherwise healthy individuals resolve on their own in a couple of weeks. Bacterial infections can get worse over time and usually require antibiotics.

A virus: One cause is the herpes cold virus, and is called acute herpetic gingivostomatitis. Another is caused by the enterovirus, and is called hand, foot and mouth disease. Check with your physician or dentist.