Scarlet Fever (Scarlatina, “Second Disease”)
Definition
• Rash in children (3–12 y/o) caused by gram+, erythrogenic, toxin-producing strains of group A β-hemolytic streptococci.
• Transmitted via airborne droplets from those w/ active dz or asymptomatic carriers as well as via fomites
History
• More prevalent in temperate climates & in early winter/spring
• Incubation period 1–4 d followed by acute onset sore throat, fever, HA, vomiting, then rash 1–2 d after sore throat. Abdominal pain may also be present & severe.
Physical Findings
• Red/scarlet colored macules on background of diffuse erythema w/ finely punctate lesions of “goose-bump” appearance, “sandpaper” texture, starts on neck/axilla/groin → trunk/extremities/face (spares palms/soles)
• Distinctive features include circumoral pallor & increased intensity at skin folds; there are often transverse red streaks in skin folds known as Pastia’s lines
• Rash resolves w/i 1 wk followed by brawny desquamation 7–10 d later
• “Strawberry” tongue, beefy red pharynx & tonsils w/ or w/o exudative effusion palatal petechiae
Evaluation
• Rapid strep test (sens 60–90%, spec 90%), throat cultures
• CBC rarely indicated but usually leukocytosis w/ PMN predominance present
Treatment
• Penicillin VK QID × 10 d, benzathine penicillin 1.2 million U IM × 1, or erythromycin in penicillin-allergic pts
Disposition
• Home
Impetigo
Definition
• Highly contagious superficial epidermal infection affecting mainly children (2–5 y/o), & is the most common bacterial skin infection in children
• Caused by S. aureus & group A β-hemolytic streptococci
• 2 types: Nonbullous & bullous impetigo
• Nonbullous impetigo accounts for majority if cases & represents a host response to infection
• Bullous impetigo is caused by bacterial toxins, particularly staphylococcal exfoliative toxins
• Transmitted via direct contact, autoinnoculation, & fomites
History
• More prevalent in early summer months
Physical Findings
• Nonbullous impetigo: Begins as red macule or papule that becomes a vesicle. Vesicle ruptures to form an erosion & its contents dry, forming honey-colored crusts; usually on face (cheeks or under lips) or extremities; self-limited over 2 wk.
• Bullous impetigo: Begins as rapidly enlarging vesicles that form sharply demarcated bullae w/ little to no surrounding erythema. These rupture, forming yellow oozing crusts; usually moist intertriginous areas involved (neck fold, axilla, groin, perineum); self-limited.
Evaluation
• Dx is clinical; gram stain & culture rarely indicated
Treatment
• Supportive care as most will resolve spontaneously
• Topical abx: Mupirocin 2% ointment to affected area TID for 3–5 d
• Oral abx may be indicated in those who cannot tolerate topical tx or w/ extensive dz: Amoxicillin/clavulanate, dicloxacillin, cephalexin, erythromycin for pen-allergic pts.
• Cx: Poststrep glomerulonephritis, cellulitis, lymphangitis, TSS, SSSS, osteomyelitis, arthritis, sepsis, endocarditis
Disposition
• Home
• Instruction to prevent spreading
(Refer to Chapter 4, “Soft Tissue Infections” for other bacterial exanthems: Erysipelas, Cellulitis, Staphylococcal Scalded Skin Syndrome, Toxic Shock Syndrome, and Necrotizing Fascitis)