Tonsillitis is an inflammation of the tonsils, two pieces of lymphoid tissue on either side of the throat. The tonsils are the immune system's first line of defense, filtering bacterial and viral organisms that enter the mouth. The tonsils can become infected by a virus or bacterial organism, resulting in pain, fever, difficulty swallowing, swollen tonsils and white patches on the tonsils.
Epstein-Barr Virus
Mononucleosis, commonly known as "the kissing disease," is a medical condition caused by the Epstein-Barr virus. Mononucleosis is transmitted via direct contact with an infected person by kissing or sharing an eating utensil. The Epstein-Barr virus infects the salivary glands and tonsils, resulting in swollen tonsils, a sore throat, fever, fatigue and swollen lymph nodes. Tonsillitis is a common complication of mononucleosis because as the sore throat worsens, the tonsils become swollen and develop a white covering, notes MedlinePlus.
Group A Streptococcus
Because the tonsils trap pathogenic organisms, they are highly vulnerable to infection and inflammation. According to MayoClinic.com, the most common bacterial organisms responsible for tonsillitis are group A streptococcus, or Streptococcus pyogenes. Bacterial organisms are responsible for 15 to 30 percent of all tonsillitis cases, notes the American Academy of Otolaryngology-Head and Neck Surgery. Bacterial infections of the tonsils are commonly treated with antibiotics such as penicillin, erythromycin and amoxicillin.
Viral Causes
According to the American Academy of Otolaryngology-Head and Neck Surgery, viral pathogens such as the herpes simplex virus, cytomegalovirus, adenovirus and the measles virus cause the majority of acute tonsillitis cases. Viral infections of the tonsils result in a sore throat, swollen tonsils, difficulty swallowing, fever and fatigue. The coxsackie virus also causes tonsillitis, as well as blistering on the mouth, throat, hands and feet.
