Brit Long, MD*; Michael Gottlieb, MD 
Peritonsillar abscess is defined as a collection of pus between the palatine tonsil capsule and the pharyngeal muscles. It most often affects the superior pole of the tonsil and, after that, the middle and inferior poles. The condition may be preceded by pharyngitis or tonsillitis, or it may occur without a preceding infection and arise as a result of obstruction of the Weber glands. Peritonsillar abscesses are often polymicrobial, including streptococcal species, staphylococcal species, and respiratory anaerobes (eg, Fusobacterium necrophorum). The annual incidence of peritonsillar abscess approximates 30 per 100,000 persons between the ages of 5 to 49 years; however, the incidence is highest in those ages 15 to 19 years, approaching 167 per 100,000.
