ByProf. Ashraf Al-Sawy MD

1. Direct infection of skin : impetigo, ecthyma,

folliculitis, furunculosis, carbuncle, sycosis.

2. Secondary infection: eczema, infestations,

ulcers, …etc.

3. Effect of bacterial toxin: staph.-associated

scalded skin syndrome (SSSS), toxic shock

syndrome.

Direct inf. of skin or subcut. tissue: Impetigo,

ecthyma, cellulitis, vulvovaginitis, perianal inf.,

strepto. ulcers, blistering distal dactylitis,

necrotizing fasciitis.

2ry inf.: eczema, infestations, ulcers, …etc.

Tissue damage from circulating toxin: scarlet

fever, toxic shock-like syndrome.

Skin lesions attributed to allergic hyper-

sensitivity to strepto. antigens: erythema

nodosum, vasculitis.

Skin dis. provoked or influenced by strepto. inf.:

psoriasis especially guttate forms.

Acute contagious skin infection caused mostly by staph. Aureus and strept.

Affects children mainly esp. in summer times.

1- Non-bullous impetigo: ◦ Caused by staph., strept. or both organisms.

2- Bullous impetigo:◦ Caused by staph aureus.

• Staph. aureus or gp A stretp. (GAS) or both

“mixed infections”.

• May arise as 1ry inf. or as 2ry inf. of pre-existing

dermatoses, e.g. pediculosis, scabies & eczemas.

• An intact st. corneum is probably the most

important defense against invasion of pathogenic

bacteria.

• A thin-walled vesicle on

erythematous base, that soon

ruptures & the exuding serum

dries to form yellowish-brown

(honey-color) crusts that dry &

separate leaving erythema

which fades without scarring.

• Regional adenitis with fever

may occur in severe cases.

Sites: Exposed parts eg. face & extremities. Scalp (in pediculosis). Any part could be affected except palms & soles.

Complications: Post-streptococcal acute glomerulo-nephritis “AGN” especially in cases due to strepto. pyogenes M. type 49.

• Circinate impetigo:

with peripheral

extension of lesion &

healing in the center.

Crusted impetigo: on the scalp

complicating pediculosis. Occipital & cervical LNs are usually enlarged & tender.

• Ecthyma (ulcerative

impetigo): adherent

crusts, beneath which

purulent irregular ulcers

occur. Healing occurs

after few wks, with

scarring.

Site: more on distal extremities (thighs & legs).

Age: all ages, but commoner in childhood & newborn (impetigo neonatorum).

Site: face is often affected, but the lesions may occur anywhere, including palms & soles.

The bullae are less rapidly ruptured (persist for 2-3 days) & become much larger. The contents are at first clear, later cloudy. After rupture, thin, brownish crusts are formed.

Treatment of predisposing causes: e.g.

pediculosis & scabies.

Remove the crusts: by olive oil or hydrogen

peroxide.

Topical antibiotic: e.g. tetracycline, bacitracin,

gentamycin, mupiracin (Bactroban®), Fusidic acid

(Fucidin®).

• Systemic antibiotics are indicated especially in the presence of fever or lymphadenopathy, in extensive infections involving scalp, ears, eyelids or if a nephritogenic strain is suspected, e.g. penicillin, erythromycin & cloxacillin.

• Azithromycin (Zithromax®) 2 caps 500 mg daily for 3 days in adults.

• In erythromycin-resistant S. aureus: amoxicillin + clavulanic a. (Augmentin®) 25 mg/kg/day.

inflammatory disease of the hair follicles,

which may be infectious or non-infectious.

Superficial Folliculitis (Bockhart’s Impetigo)

a dome-shaped pustule at the orifice of a hair follicle that heals within 7-10 days.

Caused by staph aureus and affects mainly extremities and scalp.

Topical steroids are a common predisposing factor.

Sychosis Vulgaris

• Recurrent red follicular papules

or pustules centered on a hair,

usually remain discrete over the

beard or upper lip, but may

coalesce to produce raised

plaques studded with pustules.

• DD: pseudofolliculitis of the

beard, T. barae.

Pseudofolliculitis

from penetration into the skin of sharp tips of shaved hairs.

• It is a staphylococcal infection

similar to, but deeper than

folliculitis & invades the deep

parts of the hair folliculitis.

• Occasionally several closely

grouped boils will combine to

form a carbuncle. The

carbuncle usually occurs in

diabetic cases. The site of

election is the back of the

neck.

Cellulitis is an infection of subcutaneous tissues.

Ersipelas: It’s due to infection of the dermis & upper subcutaneous tissue by gp A streptococci. The organism reaches the dermis through a wound or small abrasion. It is regarded as a superficial “dermal” form of cut. cellulitis.

Erythema, heat, swelling and pain or tenderness.

Fever and malaise which is more severe in erysipelas.

In erysipelas: blistering and hemorrhage.

Lymphangitis and lymphadenopathy are frequent.

Edge of the lesion: well demarcated and raised in erysipelas and diffuse in cellulitis.

• Recurrences may lead to lymphedema.

• Subcutaneous abscess.

• Septicemia.

• Nephritis.

• Systemic antibiotics, especially penicillin, e.g.

benzyl penicillin 600-1200 mg IV/6 hrs or

cephalosporines.

• Rest, analgesics.

Erythrasma

• It is mild, chronic,

localized superficial

infection of skin by

Coryn. Minutissimum.

• Clinically: sharply-

defined but irregular

brown, scaly patches

• usually localized to

groins, axillae, toe clefts

or may cover extensive

areas of trunk & limbs.

Obesity & DM may

coexist.

• Coral red fluorescence

under wood’s light.

• Topical treatment with azole antifungal agents

for 2 weeks or topical fucidin.

• Erythromycin orally.