BACTERIAL INFECTIONS
Impetigo contagiosa (Pyoderma) is the commonest bacterial infection in children, mostly seen during hot and humid summer seasons.
Clinically, impetigo may be nonbullous (70%) or bullous.
Nonbullous impetigo, caused by #946;-hemolytic streptococci or Staph. aureus, typical begin on exposed parts of body after a breach in skin continuity, e.g. insect bite, abrasion, scabies, etc. Initial lesions appear as a tiny vesicle or pustule, which rapidly develops into a honeycolored crusted plaque without much pain/erythema. (Fig. 25.5A). Satellite lesions are common due to spread of infection by fingers or fomites.
Bullous impetigo, caused by Staph. aureus, is mainly seen in infants and present as transparent bullae or blister, filled with turbid fluid over normal skin, mainly on face and diaper area.
Diagnosis may be confirmed by culture of the plaque or blister fluid.
D/D of bullous impetigo includes epidermolysis bullosa, herpetic infection and pemphigus.
Complications are rare and include: (a) local cellulitis, (b) regional lymphadenitis, (c) distant systemic infections, e.g. pneumonia, septicemia, arthritis/osteomyelitis, and
(c) acute post streptococcal glomerulonephritis. Rheumatic fever is rare by dermatogenic strains of #946;-hemolytic streptococci.
Management: Topical mupirocin ointment thrice a day for 7-10 days is enough in most cases, though systemic antibiotics, i.e. erythromycin (30-50 mg/kg/d for 7 days) are required in cases with wide-spread lesions or local/ regional complications. Alternatives, e.g. cloxacillin, amoxicillin/clavulinic acid or cephalosporins may be used in non-responders.
Folliculitis is the superficial infection of hair follicle, predominantly caused by Staph. aureus. Important risk factors include: Poor hygiene, moisture with maceration of skin, immunodeficiency disorders and prolonged antibiotic therapy (fungal folliculitis)
Clinically, These cases typically present over scalp, buttocks and extremities, as small, discrete, dome-shaped pustules with erythematous base (Fig.
25.5B).Treatment of folliculitis includes topical antibiotics, though severe cases may need systemic antibiotics, e.g. cloxacillin or cephalaxin.
Furuncle is a deep-seated folliculitis due to Staph. aureus, presenting as tender, indurated nodule in hair bearing area, e.g. face, axilla, buttocks and groin (Fig. 25.5C). These nodules are intensely painful, suppurate rapidly and rupture to discharge pus before healing with scar formation.
Carbuncle is the folliculitis of many contagious follicles with surrounding cellulitis and multiple drainage points. Carbuncles are common in obese, diabetic, malnourished or immunodeficient children.
Management include: (a) hot, moist compresses over closed lesions to facilitate drainage, (b) incision and drainage of large lesions, and (c) systemic cloxacillin or cephalosporin for large furuncles or carbuncles.
Erysipelas is an acute deep-seated streptococcal skin infection with lymphangitis involving face or extremities. It presents as well-defined, indurated, erythema with raised, firm borders and superficial vesiculations (Fig. 25.5D). High dose IV penicillin (2-4 Lac units/ kg/d q8hr) with/without clindamycin is the treatment of choice.
Cellulitis is a deep-seated infection of subcutaneous connective tissue, due to S. pyogenes or Staph. aureus. Lesion is similar to erysipelas but with ill-defined margins (Fig. 25.5E). Constitutional features and complications, e.g. abscess and bacteremia are common. Mild cases may
Fig. 25.5A to L: Common skin infections: (A) Impetigo; (B) Folliculitis; (C) Furuncle; (D) Erysepelas; (E) Cellulitis; (F) Scrofuloderma; (G) Tinea versicolor; (H) Tinea corporis; (I) Mucocutaneous candidiasis; (J) Warts; (K) Herpes zoster; (L) Herpes simplex*
be treated with PO cloxacillin or cephalosporin, while severe cases may need parenteral antibiotics.
Staphylococcal scalded skin syndrome is the most serious staphylococcal skin infection with generalized vesiculobullous lesions, discussed later in Ch 25.6.
Skin tuberculosis may present as: (a) erythema nodosum— a hypersensitivity manifestation, (b) scrofuloderma, (c) tuberculids, or (d) lupus vulgaris.
Lupus vulgaris, rare in children, presents as solitary, well-defined, reddish-brown plaque with atrophic center and centrifugal spread of lesion. Apple-jelly nodules are seen on pressing the lesion with a clean glass slide.
Scrofuloderma, due to contagious spread from a tubercular sinus, presents as serpiginous lesions with undermined margins surrounding the sinus (Fig. 25.5F).
25.3.2