Chapter 35. Pharyngitis

A 27-year-old woman complains of 2 days of sore throat, fever, and chills. She is unable to swallow anything other than liquids because of severe odynophagia. She denies any congestion or cough. On examination, she has bilateral tonsillar erythema and exudate (Figure 35-1). Her anterior cervical lymph nodes are tender. Based on the presence of fever, absence of cough, tender lymphadenopathy, and tonsillar exudate, she is diagnosed with a high probability of group A β-hemolytic Streptococcus (GABHS) pharyngitis and prescribed antibiotics.

Pharyngitis is inflammation of the pharyngeal tissues, and is usually associated with pain. The complaint of “sore throat” is a common one in the primary care office, and can be accompanied by other symptoms and signs including throat scratchiness, fever, headache, malaise, rash, joint and muscle pains, and swollen lymph nodes.

• Pharyngitis accounts for 1% of primary care visits.1
• Viral infections account for an estimated 60% to 90% of cases of pharyngitis.
• Bacterial infections are responsible for between 5% and 30% of pharyngitis cases, depending upon the age of the population and the season.
• The GABHS accounts for 5% to 10% of pharyngitis in adults and 15% to 30% in children.2 Up to 38% of cases of tonsillitis are because of GABHS.
• Highest prevalence in winter.
• Highest incidence in children between the ages of 4 and 7 years.
• Acute rheumatic fever is currently rare in the United States.
• Up to 14% of deep neck infections result from pharyngitis.3

• Some viruses, such as adenovirus, cause inflammation of the pharyngeal mucosa by direct invasion of the mucosa or secondary to suprapharyngeal secretions.4 Other viruses, such as rhinovirus, cause pain through stimulation of pain nerve endings by mediators, such as bradykinin.
• The GABHS releases exotoxins and proteases. Erythrogenic exotoxins are responsible for the development of the scarlatiniform exanthem (Figure 35-2). 5 Secondary antibody formation because of cross-reactivity may result in rheumatic fever and valvular heart disease.6 Antigen-antibody complexes may lead to acute poststreptococcal glomerulonephritis.
• Untreated GABHS pharyngitis can result in suppurative complications including bacteremia, otitis media, meningitis, mastoiditis, cervical lymphadenitis, endocarditis, pneumonia, or peritonsillar abscess formation (Figure 35-3). Nonsuppurative complications include rheumatic fever and poststreptococcal glomerulonephritis.

• Immune deficiency.
• Chronic irritation (e.g., allergies, cigarette smoking).

Clinical Features

• Rhinorrhea and cough are more consistent with viral etiology.
• Rapid onset odynophagia, tonsillar exudates, anterior cervical lymphadenopathy, and fever are consistent with streptococcal pharyngitis.
• Not all tonsillar exudates are caused by streptococcal pharyngitis. Mononucleosis and other viral pharyngitis can cause tonsillar exudates (Figures 35-4 and 35-5). The positive predictive value for tonsillar exudate in strep throat is only 31%; that is, 69% of patients with tonsillar exudate will have a nonstreptococcal cause.
• Para- and supratonsillar edema with medial and/or anterior displacement of the involved tonsil and uvular displacement to the contralateral side suggest peritonsillar abscess (Figure 35-3). Trismus and anterior cervical lymphadenopathy with severe tenderness to palpation are additional findings.
• Palatal petechiae can be seen in all types of pharyngitis (Figure 35-6).
• A sandpaper rash is suggestive of scarlet fever (Figure 35-2, and Chapter 34, Scarlet Fever and Strawberry Tongue).
• Lymphoid hyperplasia can cause a cobblestone pattern on the posterior pharynx or palate from viral infections, gastroesophageal reflux disease (GERD), or allergies (Figure 35-7). Although it usually is more suggestive of a viral infection or allergic rhinitis, lymphoid hyperplasia can be seen in strep pharyngitis (Figure 35-8).
• The following criteria are helpful in the diagnosis of GABHS pharyngitis:7-10
  • History of fever or temperature of 38°C (100.4°F) (1 point).
  • Absence of cough (1 point).
  • Tender anterior cervical lymph nodes (1 point).
  • Tonsillar swelling or exudates (1 point).
  • Age:
    • <15 years (1 point).
    • 15 to 45 years (0 points).
    • >45 years (−1 point).

The probability of GABHS is approximately 1% with −1 to 0 points and approximately 51% with 4 to 5 points.11

Laboratory Tests and Imaging

• Rapid antigen detection is often used to diagnose GABHS. Test options include enzyme immunoassays, latex agglutination, liposomal method, and immunochromatograph assays; the latter has the highest reported sensitivity (0.97), specificity (0.97), and positive (32.3) and negative (0.03) likelihood ratios.12
• The gold standard for the diagnosis of streptococcal infection is a positive throat culture. However, GABHS is part of the normal oropharyngeal flora in many patients and the diagnosis of acute streptococcal pharyngitis must include both the clinical signs of acute infection and a positive throat culture.
• False-positive tests for streptococcal infection can occur when the patient is colonized with GABHS but is not the cause of the acute disease.
• False-negative tests for streptococcal infection can occur when poor sampling technique with the throat swab fails to recover the streptococcal organism when it is the cause of the acute infection.
• A positive mono spot (likelihood ratio in the first week of illness 5.7) and/or greater than 40% atypical lymphocytes on the peripheral smear (likelihood ratio: 39) indicate mononucleosis.12
• Viral cultures obtained from vesicles can be obtained in Coxsackievirus and herpes infections, but the diagnosis is usually based on clinical suspicion and findings.
• Head-neck CT scan can assist in the diagnosis and localization of peritonsillar abscess and should be obtained if further extension into the deeper neck is suspected.13

• Infectious mononucleosis—Nausea, anorexia without vomiting, uvular edema, generalized symmetric lymphadenopathy, and lethargy particularly in teenagers and young adults, is more suggestive of acute mononucleosis (Epstein-Barr virus [EBV]) although the pharyngeal examination has a similar appearance to GABHS (Figure 35-4). Hepatosplenomegaly is indicative of EBV in this group.
• Herpangina/Coxsackievirus infection—Oropharyngeal vesicles and ulcers indicate herpangina, which is caused by Coxsackievirus A16 in the majority of cases (Figure 35-9).
• Oral Candida—Whitish plaques of the oropharyngeal mucosa indicate oral Candida/thrush, which is mainly found in infants but can be found in adults with immunosuppression (see Chapter 136, Candidiasis).
• Sexually transmitted infections—Primary human immunodeficiency virus, gonococcal and syphilitic pharyngitis can all present with the symptom of sore throat. Although uncommon, these diagnoses should be considered in high-risk populations.
• Primary herpes gingivostomatitis causes oral ulcers and pain in the mouth. The wide distribution of ulcers with the first case of herpes simplex virus (HSV)-1 distinguishes this infection from other types of pharyngitis (see Chapter 129, Herpes Simplex).
• Cytomegalovirus (CMV)—Primary CMV infection in the immunocompetent host is usually asymptomatic. In the immunocompromised host, CMV may present with a mononucleosis-like syndrome clinically indistinguishable from EBV infection.
• Deep neck infections—Asymmetry of the neck, neck masses, and any displacement if the peripharyngeal wall should raise suspicion. Associated shortness of breath may be a warning sign of impending airway obstruction. Other complications include aspiration, thrombosis, mediastinitis, and septic shock.13
• Epiglottitis—Rapid-onset fever, malaise, sore throat, and drooling in the absence of coughing characterize acute epiglottitis, especially when presenting in children. Progression of the disease can lead to life-threatening airway obstruction. Fortunately, this is a rare condition because of the preventive effect of the Haemophilus influenzae type b (HIB) vaccine.
• Supraglottitis—Similar symptoms to epiglottitis, although seen in adults. Sore throat and painful swallowing are the most common presenting symptoms, seen in more than 90% of cases. Muffled voice and drooling, dyspnea, stridor, and cough reported in less than 50% of cases. No definite organism is identified in the majority of cases. Unlike epiglottitis in children, HIB is responsible for less than 20% of adult cases but still accounts for the majority of positive cultures. Mortality rates have been reported up to 20%. Currently more common than epiglottitis, because of HIB vaccine.
• Diphtheria—A rare condition in the United States today, as most patients have been immunized. However, it needs to be considered, especially in unvaccinated and immigrant populations. Pharyngeal diphtheria presents with sore throat, low-grade fever, and malaise. The pharynx is erythematous with a grayish pseudomembrane that cannot be scraped off. Complications include myocarditis resulting in acute and severe congestive heart failure (CHF), endocarditis, and neuropathies.
• Other bacterial causes—Non-group A Streptococcus, Fusobacterium necrophorum, Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Arcanobacterium haemolyticum have all been isolated as bacterial causes of pharyngitis; not as clinically significant, but all generally respond to treatments prescribed for strep pharyngitis.

Nonpharmacological

• Hydration with plenty of liquids (children and adults).
• Salt-water gargles (children and adults).
• Lozenges for comfort (adults only).

Medications

• Age-appropriate dosing of acetaminophen and ibuprofen may be used for symptomatic relief of fever and pain. Doses can be alternated as needed.
• Steroids (e.g., dexamethasone single 10-mg injection) are indicated in severe tonsillitis in patients without immunocompromise.12 SOR C However, there is no good evidence to recommend steroids in infectious mononucleosis.14
• In extreme cases of pharyngitis, 1 teaspoon of viscous lidocaine 2% in a half glass of water gargled 20 to 30 minutes before meals helps the odynophagia. This is typically only recommended in rare cases because of risk of aspiration, potential toxicity of lidocaine, and the risk for oral mucosal burns—consider hospitalization if symptoms are this severe.
• Antibiotic use—Use the clinical prediction rule (given above [see “Clinical Features”]) for estimating the probability of GABHS:7-11
  • Low probability (no test, no treatment for GABHS): Patients scoring 0 points should be treated symptomatically and not given antibiotics.
  • Intermediate probability (test and treatment based on result): Patients with 1 to 3 points (probability of GABHS is approximately 18%) should undergo a rapid antigen test and be treated with antibiotics if positive.
  • High probability (no test, treatment for GABHS): Patients with 4 to 5 points should be considered for empiric antibiotic treatment.
• For suspected or proven GABHS, penicillin V 500 mg orally 2 to 3 times daily for 10 days continues to be the treatment of choice for adults.15 Erythromycin 500 mg orally 4 times daily may be used in penicillin allergic patients. Penicillin G 1.2 million U IM single dose may be used if unable to tolerate oral medication. Pediatric doses are Pen VK 25 to 50 mg/kg per day divided 3 to 4 times daily and erythromycin 30 to 50 mg/kg per day divided 4 times daily for 10 days. In some cases amoxicillin 25 mg/kg per day in divided doses every 12 hours is preferred because of palatability.
• Penicillin G (600 mg IV every 6 hours for 24 to 48 hours) in combination with metronidazole (15 mg/kg IV more than 1 hour followed by 7.5 mg/kg IV more than 1 hour every 6 to 8 hours) is recommended for peritonsillar abscess.

Referral

• If signs of airway impairment are present, the patient should be immediately transported to an emergency department. Intubation can be extremely difficult and risky.
• Refer patients with peritonsillar abscess to ear, nose, and throat (ENT). Incision and drainage is the treatment of choice in addition to using systemic antibiotics.
• Consider ENT referral for tonsillectomy in proven recurrent GABHS cases, or under certain other conditions (e.g., antibiotic allergies/intolerances) with recurrence.16 However, there is no evidence to support tonsillectomy for isolated cases.17

• Sore throat, regardless of the cause, is typically self-limiting. Typical symptoms last 3 to 4 days.
• Longer-term complications are rare but antibiotic treatment to prevent these sequelae remains justification for treatment. Antibiotics shorten the duration of illness by approximately 1 day and can reduce the risk of rheumatic fever by approximately two-thirds in communities where this complication is common.15 However, GI symptoms like mild diarrhea are common side effects of antibiotic therapy. The number needed to treat to prevent 1 sore throat at day 3 is less than 6; at week 1 it is 21.15

Follow up if clinically deteriorating, especially if swallowing or breathing becomes more difficult or severe headache develops.

• The treatment for most cases of non-GABHS pharyngitis is education. Explain to patients the difference between a viral and a bacterial infection to help them understand why antibiotics were prescribed or not prescribed. Antibiotic treatment for a patient with an obvious viral infection is inappropriate, despite patient requests. Studies demonstrate that spending time with the patient to explain the disease process is associated with greater patient satisfaction than prescribing an antibiotic.18,19
• Rest, liquids, and analgesics should be encouraged.
• Patients receiving antibiotics should be reminded to complete the entire course, even if symptoms improve. Common antibiotic side effects, like rash, nausea, and diarrhea, should be reviewed.
• Patients with mononucleosis and splenomegaly should be warned to avoid contact sports because of the risk of splenic rupture.

Patient Resources

• http://familydoctor.org/familydoctor/en/diseases-conditions/sore-throat.html.
• www.nlm.nih.gov/medlineplus/ency/article/000639.htm.
• Mononucleosis information for patients—http://familydoctor.org/familydoctor/en/diseases-conditions/mononucleosis.html.

Provider Resources

• Free clinical calculator online: Modified Centor Score for Strep Pharyngitis—http://www.mdcalc.com/modified-centor-score-for-strep-pharyngitis.