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BACTERIAL INFECTIONS

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GROUP A STREPTOCOCCAL INFECTIONS

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ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES

  • 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.

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General Considerations
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Group A streptococci (GAS) are common gram-positive bacteria producing a wide variety of clinical illnesses, including acute pharyngitis, impetigo, cellulitis, and scarlet fever. GAS can also cause pneumonia, septic arthritis, osteomyelitis, meningitis, and other less common infections. GAS infections may also produce postinfectious sequelae (rheumatic fever and acute glomerulonephritis).

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Almost all GAS are β-hemolytic. These organisms may be carried without symptoms on the skin and in the pharynx, rectum, and vagina. All GAS are sensitive to penicillin. Resistance to erythromycin is common in some countries and has increased in the United States.

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Prevention
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GAS pharyngitis usually occurs after contact with respiratory secretions of a person infected with GAS. Crowding facilitates spread of GAS and outbreaks of pharyngitis and impetigo occur. Prompt recognition and institution of antibiotics may decrease spread. Treatment with antibiotics prevents acute rheumatic fever.

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Clinical Findings
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A. Symptoms and Signs
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1. Respiratory infections

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a. Infancy and early childhood (age < 3 years)—The onset is insidious, with mild symptoms (low-grade fever, serous nasal discharge, and pallor). Otitis media is common. Exudative pharyngitis and cervical adenitis are uncommon in this age group.

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b. Childhood type— Classic GAS pharyngitis presents with the sudden onset of fever, sore throat, malaise, and often vomiting. On examination, tonsillar exudate and tender anterior cervical adenopathy are usually noted. Petechiae are frequently seen on the soft palate. In scarlet fever, the 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). The 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.

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2. Impetigo—Streptococcal impetigo begins as a papule that vesiculates and then breaks, leaving a denuded area covered by a honey-colored crust. Both Staphylococcus aureus and GAS are isolated in some cases. The 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. If flaccid bullae are noted, the disease ...

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