Strep throat: Guidelines for diagnosis and treatment
Duration of treatment
The traditional protocol is a 10-day course of penicillin, although recent studies suggest that shorter courses of treatment may be equally effective. Research shows that a 5-day course of either a cephalosporin or azithromycin is effective in eradicating streptococcal infection;18 the only drugs that are FDA approved for this regimen are cefdinir, cefpodoxime, and azithromycin.2 In addition, only cefdinir, azithromycin, cefadroxil, and cefixime are FDA approved for once-daily therapy for streptococcal infection in children.2 Since most throat cultures become negative within 24 hours of starting medication, the patient is presumed to be no longer contagious at this point and may return to school or work.19 Treatment that targets beta-hemolytic streptococci other than group A streptococci is not indicated, and antibiotic therapy for other streptococcal infection offers no symptomatic benefit.8
Management of contacts, carriers, and recurrences
The IDSA does not recommend routine throat culture or treatment of asymptomatic household contacts except in specific situations where risk of nonsuppurative complications such as RF is increased.2
As many as 20% of asymptomatic school-age children may be streptococcal carriers and can remain colonized for several months. Asymptomatic carriers do not usually need treatment because spread from carriers to close contacts is unlikely. Carriers are also at very low risk for developing suppurative or nonsuppurative complications.2
In cases where a patient is experiencing recurrent episodes of acute pharyngitis over a period of many months, subsequent positive findings on throat cultures or a positive RADT result are likely to represent a carrier state. These patients are probably experiencing nonstreptococcal infections.2 In the case of “ping-pong” spread of infection in a household, try to obtain specimens simultaneously from all family members and treat those for whom culture results are positive. There is no evidence that family pets are reservoirs for GABHS.
Other group A beta-hemolytic streptococcal infections
Scarlet fever The clinical manifestations of scarlet fever (scarlatina) are the result of an erythrogenic toxin produced by GABHS. Although scarlet fever usually follows streptococcal pharyngitis, it may also follow streptococcal infection at other sites on the affected patient. The patient, usually 5 to 15 years old, develops circumoral pallor with petechiae on all mucosal surfaces. The rash first appears 12 to 24 hours after the onset of illness.20 The skin appears diffusely erythematous, sunburned, and roughened; this is the typical sandpaper rash so characteristic of scarlet fever. The rash is more pronounced in the skinfolds of the neck, groin, and axillae, producing confluent lines of petechiae referred to as Pastia's lines.6 The rash, which is caused by increased capillary fragility, begins to fade in 3 to 4 days and then desquamates, first on the face and then on the palms. Desquamation becomes generalized in about a week.
The tongue also has a characteristic appearance in scarlet fever. During the first few days, it has a white coating and has red, edematous papillae, the so-called white strawberry tongue. After about 2 days, the tongue desquamates and appears beefy red with prominent papillae; it is then called a strawberry tongue (see the September 2005 print issue of JAAPA for Figure 1).20
Perianal streptococcal cellulitis This is a unique pediatric infection, occurring mainly in children 6 months to 10 years of age.21 Patients may present with blood-streaked stools or constipation secondary to painful defecation. Other signs and symptoms include perianal dermatitis in 90% of patients and perianal itching in 78% (see the September 2005 print issue of JAAPA for Figure 2).22 Physical examination reveals perianal erythema and tenderness. Diagnosis is confirmed by RADT or culture of a perirectal swab specimen, which usually grows out copious amounts of the organism. Digital self-contamination from an infected oropharynx or skin lesion may be the source of the infection. Streptococcal vaginitis is a variant form of this condition seen in prepubescent females. Signs and symptoms include a clear vaginal discharge, vulvar erythema, and dysuria. Vulvar pain can be so severe that it causes painful ambulation. Differential diagnosis of these conditions includes candidiasis, psoriasis, sexual abuse, and pinworms.
Treatment for perianal streptococcal cellulitis, as for streptococcal pharyngitis, is with amoxicillin, penicillin, erythromycin, or a cephalosporin. Treatment is often delayed because of misdiagnosis but generally resolves the disorder rapidly.
Impetigo Nonbullous impetigo is a superficial infection of the skin caused by GABHS. Mixed infection with staphylococci is common. Bullous impetigo, however, is a distinct entity caused by Staphylococcus aureus.23 Primary GABHS impetigo infection is usually precipitated by minor trauma or insect bites that cause a break in the skin; secondary impetiginization is common in certain underlying dermatoses, specifically atopic dermatitis, herpetic infections, and scabies. Most cases occur in young children and adolescents. Impetigo occurs most commonly during the summer months in temperate climates and year round in warm, humid regions.23 Erythematous papules turn into vesicles that rupture, forming shallow erosions with the characteristic honey-colored crust (see the September 2005 print issue of JAAPA for Figure 3). Pruritus is variable, and systemic symptoms, though rare, can occur.
Erysipelas is a GABHS infection of the deeper dermis and subcutaneous tissues. Look for well-demarcated, shiny, erythematous plaques on the lower extremities, usually along with systemic symptoms.
Treatment of localized nonbullous impetigo is with 2% mupirocin ointment; treatment of widespread impetigo or erysipelas is with beta-lactamase-resistant penicillin or a first-generation cephalosporin.23