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PATIENT STORY

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 37-1). Her anterior cervical lymph nodes are tender. Based on the presence of fever, absence of cough, tender lymphadenopathy, and tonsillar exudate, you believe that she has a high probability of group A β-hemolytic Streptococcus (GABHS) pharyngitis. A rapid antigen detection test confirms the diagnosis, and you prescribe antibiotics.

FIGURE 37-1

Strep pharyngitis showing tonsillar exudate and erythema. (Reproduced with permission from Richard P. Usatine, MD.)

INTRODUCTION

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.

EPIDEMIOLOGY

  • Pharyngitis accounts for 1% of primary care visits.1

  • Viral infections account for an estimated 60% to 90% of cases of pharyngitis.

  • In patients ages 16–20 years, 1 in 13 presenting with sore throat have mononucleosis.2

  • Bacterial infections are responsible for between 5% and 30% of pharyngitis cases, depending on the age of the population (higher rates among children ages 4–7 years) and season (highest in winter).

  • The GABHS accounts for 5% to 15% of pharyngitis in adults and 20% to 30% in children.3 Up to 38% of cases of tonsillitis are because of GABHS.

  • Acute rheumatic fever is currently rare in the United States.

  • Up to 14% of deep neck infections result from pharyngitis.4

ETIOLOGY AND PATHOPHYSIOLOGY

  • Some viruses, such as adenovirus, cause inflammation of the pharyngeal mucosa by direct invasion of the mucosa or secondary to suprapharyngeal secretions.5 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 37-2).6 Secondary antibody formation because of cross-reactivity with the M protein (a virulence factor located peripherally on the cell wall) 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 37-3). Nonsuppurative complications include rheumatic fever and poststreptococcal glomerulonephritis.

FIGURE 37-2

Scarlatiniform rash in scarlet fever. This 7-year-old boy has a typical sandpaper rash with his strep throat and fever. The erythema is particularly concentrated in the axillary area. (Reproduced with ...

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