A throat infection, also known as strep throat, is an infection of the throat caused by bacteria. It is characterized by a sore throat, fever, and swollen lymph nodes in the neck. Strep throat is the most common type of throat infection and is caused by the Streptococcus bacteria. Symptoms include a sore throat, fever, difficulty swallowing, and swollen lymph nodes in the neck. Treatment typically involves antibiotics and rest.