Etiology and Pathogenesis

There are numerous causes of pharyngitis, including infection, allergic rhinitis, environmental exposures, gastroesophageal reflux, and malignancy. The most common type of pharyngitis, however, is acute infectious pharyngitis, which is the focus of this chapter (Table 35-1). Viral infectious account for 40% to 60% of pediatric pharyngitis and usually present as part of a larger viral syndrome. Rhinovirus, adenovirus, and coronavirus, for example, present with sore throat along with fever, rhinorrhea, and other cold symptoms. Pharyngitis secondary to Epstein-Barr virus (EBV), on the other hand, commonly presents in adolescents and young adults as a symptom of mononucleosis syndrome.

Table 35-1 Common Causes of Acute Infectious Pharyngitis

CMV, cytomegalovirus; EBV, Epstein-Barr virus; GABHS, group A β-hemolytic streptococci; HSV, herpes simplex virus; RSV, respiratory syncytial virus.

Alternatively, various bacteria may cause acute infectious pharyngitis. Streptococcus pyogenes, also known as group A β-hemolytic streptococci (GABHS), is the most common bacterial cause of pharyngitis. It accounts for 15% to 30% of pediatric pharyngitis and is an important pathogen to identify because treatment is essential in reducing the risk of postinfectious complications. Other common bacterial pathogens as well as a few fungal pathogens that can cause pharyngitis are listed in Table 35-1.

Most infectious pathogens, including GABHS, cause pharyngitis by directly invading the pharyngeal mucosa and causing a local inflammatory response. A few pathogens, however, such as rhinovirus, respiratory syncytial virus (RSV), and coronavirus, primarily affect the nose by increasing secretions and mucus production, which then causes a secondary irritation of the pharyngeal mucosa and resulting pharyngitis symptoms.

Clinical Presentation

The presenting signs and symptoms surrounding pharyngitis can vary from one patient to another, yet some clinical findings are fairly typical of acute infectious pharyngitis. The most common findings in those with infectious pharyngitis include a history of fever; cervical lymphadenopathy; and oropharyngeal or tonsillar erythema, enlargement, or exudates (Figure 35-2). Although no definitive clinical presentations can correctly identify the cause of an individual’s pharyngitis, various signs and symptoms are more characteristic of one pathogen than another. These common presentations include:

Figure 35-2 Tonsillitis.

Finally, epiglottitis, croup, retropharyngeal abscesses, and peritonsillar abscesses can present similarly to pharyngitis but usually have other differentiating signs such as asymmetric tonsils (peritonsillar abscess), limited extension of the neck (retropharyngeal abscess), stridor and barky cough (croup), and toxic appearance with tripod positioning (epiglottitis). These diseases often require more acute intervention at the time of presentation and are discussed in more detail in other chapters of this textbook.

Evaluation and Management

As with any patient, airway management is paramount and airway patency should be the first step in assessing a patient with pharyngitis. Additionally, hydration status should be evaluated because patients with severe odynophagia may have minimal oral intake and become severely hydrated. After management of these potentially life-threatening complications, attention can be turned to management of the pharyngitis itself.

Most cases of infectious pharyngitis are self-limited, and supportive measures provide adequate treatment. Management often includes pain and fever control with acetaminophen, ibuprofen, or both; maintaining adequate hydration status; and clearing secretions through nasal suctioning and chest physiotherapy. Some physicians may use a short course of steroids for patients with potential airway compromise or to provide symptomatic relief in those with extreme pain, but there is little evidence supporting the effectiveness of steroids in the management of acute pharyngitis.

Although most cases of acute infectious pharyngitis resolve spontaneously within 3 to 7 days, the purpose of a diagnostic workup is to identify and treat pathogens that have potentially harmful sequelae (see Table 35-2 for common diagnostic testing). In particular, GABHS is the only common form of pharyngitis for which antimicrobial therapy is definitively indicated because it can prevent complications of the illness, most importantly, acute rheumatic fever (Figure 35-3). The additional benefits that come from antimicrobial treatment of GABHS are a reduction in the incidence of toxic shock syndrome, peritonsillar or retropharyngeal abscesses, cervical lymphadenitis, and mastoiditis. The one sequela of GABHS that is not prevented by adequate treatment of strep pharyngitis is poststreptococcal glomerulonephritis.

Table 35-2 Diagnostic Testing for Infectious Pharyngitis

CMV, cytomegalovirus; EBV, Epstein-Barr virus; GABHS, group A β-hemolytic streptococci; HSV, herpes simplex virus; PCR, polymerase chain reaction; RADT, rapid antigen detection test.

Figure 35-3 Rheumatic fever.

The two tests most commonly used to diagnose GABHS are rapid antigen detection testing (RADT) and throat culture. When the swab is performed correctly, throat culture is the gold standard for diagnosis and has a sensitivity of greater than 90% and specificity close to 99%. RADT, however, has a high specificity of approximately 95% but a relatively low sensitivity of 80% to 90%. Because of the high rate of false-negative results with RADT compared with throat culture, the American Academy of Pediatrics, the Infectious Disease Society of America, and the American Heart Association recommend that all negative RADT results be confirmed by throat culture.

If RADT or throat culture results are positive, the first line treatment for GABHS is penicillin V taken orally two or three times per day for 10 days, a single intramuscular dose of penicillin G, or a single 50-mg/kg daily dose of amoxicillin for 10 days. Alternative therapies in penicillin-allergic patients include cephalosporins, erythromycin, azithromycin, and clindamycin. Because there has not yet been a documented case of penicillin-resistant GABHS around the world, penicillin remains the treatment of choice in those who are not allergic to the medication.

Throat cultures can also be used to identify other bacterial causes of pharyngitis, but many laboratories will not look for additional organisms unless specifically asked to do so. If a child’s history and clinical presentation raise suspicion for an alternative source of infection, clinicians must remember that culture requirements may be different for the various pathogens (see Table 35-2). N. gonorrhoeae, for instance, requires Thayer-Martin culture medium for growth and Corynebacterium diphtheria grows on Loeffler agar or tellurite agar. Chlamydia pneumoniae, on the other hand, is most commonly detected by fluorescent monoclonal antibody testing.

The treatment of patients with bacterial pharyngitis differs based on the causative pathogen (Table 35-3). Neisseria spp. are most commonly treated with a single dose of intramuscular ceftriaxone along with azithromycin or doxycycline for empiric treatment of possible Chlamydia co-infection. Diphtheria, a disease more commonly found in unimmunized children, can lead to severe respiratory obstruction depending on the location of the pseudomembranes (Figure 35-4). Additionally, the toxin released by the bacteria can cause life-threatening neurotoxicity and cardiac toxicity. Therefore, the treatment for diphtheria includes both an antitoxin to counter the toxin in conjunction with penicillin or erythromycin to reduce the bacterial load. Other bacteria such as non-GABHS and Arcanobacterium haemolyticum rarely require antimicrobial treatment.

Table 35-3 Pharmacologic Management of Acute Infectious Pharyngitis

GABHS, group A β-hemolytic streptococci; HSV, herpes simplex virus.

* Treatment is not routinely indicated but may be used in children with specific comorbidities or clinical presentations.

Figure 35-4 Infections of pharynx.

With respect to viral pathogen identification, testing for the common viruses such as rhinovirus or coronavirus is not routinely indicated because identification of the pathogen will not change management of the patient. In immunocompromised patients or those with certain comorbid conditions, however, identification of adenovirus, influenza, or RSV can be useful because treatment may be indicated in these high-risk populations (see Table 35-3).

Unlike identification of the viruses that cause common cold symptoms, diagnosis of HSV, HIV, and EBV is important in all populations so patients can receive the appropriate anticipatory guidance and treatment. HSV is most commonly diagnosed with polymerase chain reaction or viral culture, and infected patients can be treated with either acyclovir or valacyclovir. HIV testing is done by antibody testing or RNA analysis, and if the results are positive, treatment with antiretrovirals as well as appropriate anticipatory guidance for reducing the risk of transmission are imperative.

The diagnosis of EBV is unique in that workup can vary based on stage of illness. Heterophile antibody testing (monospot test) is up to 95% sensitive and should be considered for all patients presenting with a high clinical suspicion of infectious mononucleosis. Unfortunately, monospot may be falsely negative in those presenting early in their illness (during the first 2 weeks) and in those younger than 4 years of age. In these cases, a peripheral smear with an atypical lymphocytosis can be indicative of mononucleosis, and EBV serology may be diagnostic. For children and adolescents diagnosed with EBV, it is imperative to give patients appropriate anticipatory guidance to reduce the risk of splenic injury. But as with most cases of pharyngitis, the mainstay of treatment is supportive care.

Future Directions

Although pharyngitis tends to be a fairly benign process, the morbidity and cost to society resulting from pain, clinical visits, missed school days, and missed work is significant. Therefore, finding a way to decrease the pathologic burden of disease could be beneficial in reducing the cost to society. One potential method, the development of a vaccine against GABHS, would minimize not only the incidence of disease but also the suppurative and nonsuppurative complications that can follow GABHS pharyngitis. Another potential area for improvement arises in the context of antibiotic use. Because 10% to 15% of children are asymptomatic carriers of GABHS, clinicians need a better algorithm to discern which patients have a high pretest probability of GABHS pharyngitis so that GABHS carriers with viral pharyngitis are not receiving unnecessary antibiotics. Such a decision rule would reduce overtreatment and in turn minimize antibiotic exposure and the potential for antibiotic resistance.