Pharyngitis, or sore throat, is often caused by infection. Common respiratory viruses account for the vast majority of cases (see Viral Pharyngitis), and these are usually self-limited. Bacteria are also important etiologic agents, and, when identified properly, may be treated with antibacterials, resulting in decreased local symptoms and prevention of serious sequelae.
The most common and important bacterial cause of pharyngitis is Streptococcus pyogenes (group A Streptococcus [GAS]). When suspected, bacterial pharyngitis should be confirmed with routine diagnostic tests and treated with various antibiotics. Swabbing the throat and testing for GAS pharyngitis via rapid antigen detection test (RADT) and/or culture should be performed as clinical features alone cannot reliably distinguish GAS pharyngitis from viral pharyngitis. The exceptions to these is when patients present overt clinical features of viral infection including rhinorrhea, cough, oral ulcers, and/or hoarseness, in which case a positive test result might reflect a carriage state.
If left untreated, S pyogenes pharyngitis may lead to local and distant complications. To a lesser extent, bacteria other than S pyogenes are known to cause pharyngitis, and these are discussed in Causes.