33-01: Streptococcal Infections

Group A beta-hemolytic streptococci (Streptococcus pyogenes) are the most common bacterial cause of pharyngitis. See Pharyngitis & Tonsillitis in Chapter 8.

1. ACUTE RHEUMATIC FEVER & SCARLET FEVER

General Considerations

Group A streptococci producing erythrogenic toxin may cause scarlet fever in susceptible persons. Acute rheumatic fever may follow recurrent episodes of pharyngitis beginning 1–4 weeks after the onset of symptoms. Effectively controlling rheumatic fever depends on identification and treatment of primary streptococcal infection and secondary prevention of recurrences.

Glomerulonephritis is another rare complication, following a single infection with a nephritogenic strain of streptococcus group A (eg, types 4, 12, 2, 49, and 60), more commonly on the skin than in the throat, and begins 1–3 weeks after the onset of the infection.

Clinical Findings

S pyogenes (group A Streptococcus [GAS]) pharyngitis is usually a self-limited condition, lasting 3–5 days. The rash of scarlet fever (also called scarletina) is diffusely erythematous and resembles a sunburn, and superimposed fine red papules give the skin a sandpaper consistency; it is most intense in the groin and axillas (eFigure 33–1). It blanches on pressure, may become petechial, and fades in 2–5 days, leaving a fine desquamation. The face is flushed, with circumoral pallor, and the tongue is coated with enlarged red papillae (strawberry tongue). The diagnosis is clinical in the setting of streptococcal pharyngitis. The diagnosis of acute rheumatic fever relies on a constellation of signs, symptoms, and laboratory findings, known as the Jones criteria: major criteria include presence of pancarditis, polyarthritis, subcutaneous nodules, erythema marginatum, chorea, and minor criteria include presence of heart block, arthralgia, elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), fever, leukocytosis, or history of prior rheumatic fever. At least two major Jones criteria or one major and two minor criteria plus evidence of recent GAS infection by either bacterial culture data, rapid strep testing, or elevated anti-strep antibody titers are required to establish a diagnosis. These complications are more common in children.

Treatment

Antimicrobial therapy of pharyngitis may reduce the risk of complications (see Chapter 8). There is no additional treatment of scarlet fever or acute rheumatic fever beyond that of the underlying streptococcal pharyngitis.

Prevention of Recurrent Rheumatic Fever

Patients who have had rheumatic fever should be treated with a continuous course of antimicrobial prophylaxis for at least 5 years. Effective regimens are erythromycin, 250 mg orally twice daily, or penicillin G, 500 mg orally daily.