Tonsillitis, or inflammation of the tonsils, makes up approximately 0.4% of outpatient visits in the United States and is usually caused by a viral infection.^1–3 Transmission occurs via droplets from patients with acute tonsillitis or rarely by asymptomatic carriers.³ Tonsilloliths, or tonsil stones, may be a result of recurrent tonsillitis, although the exact cause is unclear.

Tonsillitis

The tonsils are located in the lateral oropharynx between the anterior palatoglossal arch and the posterior palatopharyngeal arch. Tonsillitis is caused by a viral infection in 70% to 95% of cases.^2,3 The most common viral causes include rhinovirus, respiratory syncytial virus, adenovirus, and coronavirus. Less common causes include Epstein-Barr virus, cytomegalovirus, hepatitis A, and rubella. Bacterial infections caused by group A beta-hemolytic streptococcus (GABHS) account for tonsillitis in 5% to 15% of adults and 15% to 30% of patients five to 15 years of age. Viral etiologies are more common in children younger than five years, and GABHS is rare in children younger than two years.²

Tonsillitis is less commonly caused by other bacteria such as groups C and G streptococci, Hemophilus influenzae, Nocardia, and Corynebacteriaceae.³ Syphilis, gonorrhea, chlamydia, and HIV should be considered in sexually active patients. Tuberculosis can cause recurrent tonsillitis.² Only one-half to two-thirds of patients with tonsillitis have a detectable pathogen.³

CLINICAL MANIFESTATIONS

Acute tonsillitis is an inflammatory process of the tonsillar tissues. It may occur in isolation or as part of a generalized pharyngitis.⁴ The most common symptoms are fever, tonsillar exudate, sore throat, and tender anterior cervical lymphadenopathy⁵ (Figure 1⁶). Other symptoms include odynophagia and dysphagia, particularly if tonsillar swelling is present. On physical examination, the tonsils may appear enlarged or erythematous, decreasing visualization of the posterior oropharynx. Tonsillar exudate can appear yellow or white.² Data have shown that palatal petechiae are associated with GABHS pharyngitis and tonsillitis and are possibly more predictive than the presence of tonsillar exudate.⁷

DIAGNOSIS

The differential diagnosis of tonsillitis includes pharyngitis, retropharyngeal abscess, epiglottitis, peritonsillar abscess, and submandibular space infections (Ludwig angina).² It is important to differentiate GABHS pharyngitis and tonsillitis from other bacterial and viral causes due to the risk of complications with GABHS.⁴ Physical examination of the oropharynx alone is not sufficient for this differentiation; therefore, a clinical scoring scale, such as the widely used Centor score (Table 1^8,9), is recommended to guide diagnosis and treatment of GABHS oropharyngeal infections.

The Centor score was developed in 1981 based on a study of 286 adults from a single emergency department.^8,10 A second clinical scoring system, the McIsaac score/modified Centor score (https://www.mdcalc.com/centor-score-modified-mcisaac-strep-pharyngitis) was developed in 1998 based on 621 children and adults from 49 Ontario, Canada, communities.⁸ This score adds an adjustment for the patient's age because GABHS infections are more prevalent in younger patients. Because the initial sample sizes supporting these scores were small, both scoring systems underwent large-scale validation.⁸ A meta-analysis comparing the two scoring systems in a primary care setting found that they were similar in performance.⁹