Acute Pharyngitis, Tonsillitis, and Peritonsillar Abscess

This chapter reviews the epidemiology, microbiology, clinical features, differential diagnosis, and treatment of pharyngitis and peritonsillar abscess. Most cases of pharyngitis are viral, but distinguishing viral from bacterial infections clinically is difficult. A polymerase chain reaction (PCR) test, rapid antigen detection test, and/or throat culture is required to distinguish viral pharyngitis from pharyngitis due to group A Streptococcus, although a clinical scoring system can be helpful in predicting viral cases. Fusobacterium necrophorum, an anaerobe, is not identified on routine throat culture, yet it is a common cause of pharyngitis and peritonsillar abscess in adolescents and young adults. Peritonsillar abscess usually requires surgical drainage by needle aspiration or incision, in addition to antibiotic therapy. In this update, we discuss new pathogens associated with pharyngitis, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Mpox (formerly Monkeypox), which have emerged in recent years.