Group A Streptococcal Infections

Key Features

Essentials of Diagnosis

Streptococcal pharyngitis

• Clinical diagnosis based entirely on symptoms; signs and physical examination unreliable

• Throat culture or rapid antigen detection test positive for group A streptococci

Impetigo

• Rapidly spreading, highly infectious skin rash

• Erythematous denuded areas and honey-colored crusts

• Group A streptococci are grown in culture from most (not all) cases

General Considerations

• Group A streptococci (GAS) produce a wide variety of clinical illnesses, including acute pharyngitis, impetigo, cellulitis, and scarlet fever

• Can also cause pneumonia, septic arthritis, osteomyelitis, meningitis, and other less common infections

• May also produce postinfectious sequelae (rheumatic fever and acute glomerulonephritis).

• Almost all GAS are β-hemolytic

Clinical Findings

Symptoms and Signs

• Respiratory infections in children younger than 3 years

  • Onset is insidious

  • Symptoms are mild (low-grade fever, serous nasal discharge, and pallor)

  • Otitis media is common

  • Exudative pharyngitis and cervical adenitis are uncommon in this age group

• Respiratory infections in children older than 3 years

  • Presents with the sudden onset of fever, sore throat, malaise, and often vomiting

  • Tonsillar exudate and tender anterior cervical adenopathy are usually noted

  • Petechiae are frequently seen on the soft palate

• Scarlet fever

  • Skin is diffusely erythematous and appears sunburned and roughened (sandpaper rash); most intense in the axillae, groin, and on the abdomen and trunk

  • It blanches except in the skin folds, which do not blanch and are pigmented (Pastia sign)

  • Rash usually appears 24 hours after the onset of fever and rapidly spreads over the next 1–2 days

  • Desquamation begins on the face at the end of the first week and becomes generalized by the third week

  • Early in the infection, there is circumoral pallor and the surface of the tongue is coated white, with the papillae enlarged and bright red (white strawberry tongue)

  • Subsequently desquamation occurs, and the tongue appears beefy red (strawberry tongue)

  • Petechiae may be seen on any mucosal surfaces

• Impetigo

  • Begins as a papule that vesiculates and then breaks, leaving a denuded area covered by a honey-colored crust

  • Lesions spread readily and diffusely

  • Local lymph nodes may become swollen and inflamed

  • Although the child often lacks systemic symptoms, a high fever and toxicity may be present

• Cellulitis

  • Local acute lymphadenitis occurs

  • Child is usually acutely ill, with fever and malaise

  • Streptococcal perianal cellulitis

    • Causes pain with defecation, often leadings to constipation

    • Perianal erythema, tenderness, and painful rectal examination are only abnormal physical findings

    • Scant rectal bleeding with defecation may occur

  • Streptococcal vaginitis is a variant of perianal cellulitis

    • Symptoms are dysuria and pain

    • Marked erythema and tenderness of the introitus and blood-tinged discharge are seen

• Necrotizing fasciitis

  • About 20–40% of cases are due to GAS

  • Characterized by extensive necrosis of superficial fasciae, undermining of surrounding tissue, and usually systemic toxicity

• Streptococcal sepsis

  • Rash and scarlet fever may be ...