Prof. Ashraf Al-Sawy MD
1. Direct infection of skin : impetigo, ecthyma,
folliculitis, furunculosis, carbuncle, sycosis.
2. Secondary infection: eczema, infestations,
3. Effect of bacterial toxin: staph.-associated
scalded skin syndrome (SSSS), toxic shock
Direct inf. of skin or subcut. tissue: Impetigo,
ecthyma, cellulitis, vulvovaginitis, perianal inf.,
strepto. ulcers, blistering distal dactylitis,
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
Skin dis. provoked or influenced by strepto. inf.:
psoriasis especially guttate forms.
Acute contagious skin infection
caused mostly by staph. Aureus and
Affects children mainly esp. in
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
• 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
• 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.
“AGN” especially in
cases due to strepto.
pyogenes M. type 49.
• Circinate impetigo:
extension of lesion &
healing in the center.
on the scalp
& cervical LNs are
usually enlarged &
• Ecthyma (ulcerative
crusts, beneath which
purulent irregular ulcers
occur. Healing occurs
after few wks, with
Site: more on distal
extremities (thighs &
Age: all ages, but
childhood & newborn
Site: face is often
affected, but the
lesions may occur
palms & soles.
The bullae are less
(persist for 2-3 days)
& become much
larger. The contents
are at first clear, later
cloudy. After rupture,
thin, brownish crusts
Treatment of predisposing causes: e.g.
pediculosis & scabies.
Remove the crusts: by olive oil or hydrogen
Topical antibiotic: e.g. tetracycline, bacitracin,
gentamycin, mupiracin (Bactroban®), Fusidic acid
• 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.
pustule at the orifice
of a hair follicle that
heals within 7-10
Caused by staph
aureus and affects
Topical steroids are a
• 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.
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
Cellulitis is an infection of subcutaneous
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
swelling and pain or
Fever and malaise
which is more severe in
In erysipelas: blistering
Edge of the lesion:
well demarcated and
raised in erysipelas
and diffuse in
• Recurrences may lead to lymphedema.
• Subcutaneous abscess.
• Systemic antibiotics, especially penicillin, e.g.
benzyl penicillin 600-1200 mg IV/6 hrs or
• Rest, analgesics.
• It is mild, chronic,
infection of skin by
• 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
• Coral red fluorescence
under wood’s light.
• Topical treatment with azole antifungal agents
for 2 weeks or topical fucidin.
• Erythromycin orally.