Tonsillitis in adults is primarily caused by infections, most commonly viral but sometimes bacterial.
Causes of Tonsillitis in Adults
- Viral infections are the predominant cause, responsible for about 70% of cases. Common viruses include cold viruses, adenoviruses, Epstein-Barr virus (which causes mononucleosis), herpes simplex virus, cytomegalovirus, influenza virus, and measles virus. These viruses generally cause tonsillitis as part of broader upper respiratory infections.
- Bacterial infections cause a smaller but clinically important portion of tonsillitis. The most common bacterial cause is Group A beta-hemolytic Streptococcus (Streptococcus pyogenes), often referred to as strep throat. Other bacteria that may cause tonsillitis include Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Fusobacterium necrophorum. Less common bacterial agents include Mycoplasma pneumoniae, Chlamydophila pneumoniae, Neisseria gonorrhoeae, and Corynebacterium diphtheriae in some cases.
Additional Factors
- Tonsils are lymphatic tissue with irregular surfaces where viruses and bacteria can accumulate and cause inflammation or infection.
- Risk factors for adult tonsillitis include still having tonsils (some adults have not had them removed), living or working closely with children who are more prone to tonsillitis, and age-related immune system changes, especially in the elderly.
In summary, tonsillitis in adults is caused mainly by viral infections but can also result from bacterial infections, especially group A streptococcus. The tonsils' anatomy and exposure to infectious agents contribute to their inflammation.
