Pharyngitis After an incubation period of 1-4 days, pts develop sore throat, fever, chills, malaise, and GI manifestations.
- Examination may reveal an erythematous and swollen pharyngeal mucosa, purulent exudates over the posterior pharynx and tonsillar pillars, and tender anterior cervical adenopathy.
- Viral pharyngitis is the more likely diagnosis when pts have cough, coryza, hoarseness, conjunctivitis, or mucosal ulcers.
- Throat culture is the gold standard for diagnosis.
- - Latex agglutination or enzyme immunoassay is highly specific (>95%) and can be relied on for a rapid, definitive diagnosis.
- - Given a variable sensitivity of 55-90%, a negative rapid-assay result should be confirmed with a throat culture.
Treatment: GAS Pharyngitis - See Table 87-1 for recommended treatments.
- - The primary goal of treatment is to prevent suppurative complications (e.g., lymphadenitis, abscess, sinusitis, bacteremia, pneumonia) and ARF; therapy does not seem to significantly reduce the duration of symptoms or to prevent PSGN.
- - Follow-up cultures after completion of therapy are not routinely recommended.
- Asymptomatic pharyngeal GAS carriage usually is not treated; however, when the pt is a potential source of infection in others (e.g., health care workers), either clindamycin (300 mg PO tid for 10 days) or penicillin V (500 mg PO qid for 10 days) with rifampin (300 mg PO bid for the first 4 days) is used.
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Scarlet Fever Scarlet fever is the designation for GAS infection—usually pharyngitis—associated with a characteristic rash. It is much less common now than in the past.
- The rash typically appears in the first 2 days of illness over the upper trunk and spreads to the extremities but not to the palms and soles. The skin has a sandpaper feel.
- Other findings include circumoral pallor, strawberry tongue (enlarged papillae on a coated tongue), and Pastia's lines (accentuation of rash in skin folds).
- Rash improves in 6-9 days, with desquamation on palms and soles.
Skin and Soft Tissue Infections See Chap. 84. Infections of the Skin, Soft Tissues, Joints, and Bones for further discussion of clinical manifestations and treatment.
- Impetigo: A superficial skin infection, impetigo is most often seen in young children in warmer months or climates and under poor hygienic conditions.
- - Red papular lesions evolve into pustules that ultimately form characteristic honeycomb-like crusts, usually affecting the facial areas around the nose and mouth and the legs. Pts are usually afebrile.
- - GAS impetigo is associated with PSGN but not with ARF.
- - For treatment, see Table 87-1. Given an increasing incidence of impetigo due to Staphylococcus aureus, empirical antibiotic therapy should cover GAS and S. aureus.
- Thus dicloxacillin or cephalexin (250 mg PO qid for 10 days) is used.
- Topical mupirocin ointment is also effective.
- Cellulitis: GAS cellulitis develops at anatomic sites where normal lymphatic drainage has been disrupted (e.g., by surgery or prior cellulitis). When skin integrity is breached, organisms may enter at sites distant from the area of cellulitis.
- - GAS may cause rapidly developing postoperative wound infections with a thin exudate.
- - Erysipelas is a form of cellulitis characterized by pain, fever, and acute onset of bright red swelling that is sharply demarcated from normal skin.
- It usually involves the malar facial area or the lower extremities and is caused almost exclusively by β-hemolytic streptococci, usually GAS.
- The skin often has a peau d'orange texture, and blebs or bullae may form after 2 or 3 days.
- - For treatment of erysipelas or cellulitis known to be due to GAS, see Table 87-1; empirical treatment should be directed against GAS and S. aureus.
- Necrotizing fasciitis: See Chap. 84. Infections of the Skin, Soft Tissues, Joints, and Bones for details. GAS causes ~60% of cases of necrotizing fasciitis. For treatment, see Table 87-1.
Pneumonia and Empyema GAS is an occasional cause of pneumonia in previously healthy pts.
- Pts have pleuritic chest pain, fever, chills, and dyspnea; ~50% have accompanying pleural effusions that—unlike the sterile parapneumonic effusions of pneumococcal pneumonia—are almost always infected and should be drained quickly to avoid loculation.
- For treatment, see Table 87-1.
Bacteremia In most cases of GAS bacteremia, a focus is readily identifiable. Bacteremia occurs occasionally with cellulitis or pneumonia and frequently with necrotizing fasciitis.
- If no focus is immediately evident, a diagnosis of endocarditis, occult abscess, or osteomyelitis should be considered.
Toxic Shock Syndrome Unlike those with TSS due to S. aureus, pts with streptococcal TSS generally lack a rash, have bacteremia, and have an associated soft tissue infection (cellulitis, necrotizing fasciitis, or myositis).
- Table 87-2 presents a proposed case definition for streptococcal TSS.
- The mortality rate for streptococcal TSS is ≥30%, with most deaths due to shock and respiratory failure.
- For treatment, see Table 87-1.