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.

Mechanical disruption (inflammations, abrasions)

Prolonged use of steroids, topical or systemic

Presence of systemic illnesses (DM, malignancy)

Immunosuppression MalnutritionAnaemia

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 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.

A mother brings 5 yr old Johnny to

surgery. He has developed this rash, which is weeping and

crusting.

What is the diagnosis?

A highly infectious skin disease, which commonly occurs in children.

What is the likely causative organism?

The causative organism is usually Staphylococcus Aureus or can be strep pyogenes.

What is the treatment?

Treatment: Mild localised cases - use topical antibiotic

Polyfax Widespread or more severe infections – use

systemic antibiotics, such as flucloxacillin (or erythromycin if penicillin allergic)

A: He does not have to be excluded from school so long as he is on antibiotics

B: He has to remain off of school for 5 days from the onset of the lesions

C: He must remain off of school until the lesions have crusted or healed

D: He must remain off of school until he has completed the antibiotic course.

A 27 year old business man

attends surgery complaining of

pain and itching in the beard area. You

examine him and see the following:

What is the Diagnosis?

Inflammation of the hair follicle.

Presents as itchy or tender papules and pustules at the follicular openings.

Complications include abscess formation and cavernous sinus thrombosis if upper lip, nose or eye affected.

What is the causative organism?

Most common cause is Staph Aureus.Other organisms to consider include:Gram negative bacteria – usually in

patients with acne who are on broad spec antibiotics

Pseudomonas (“Hot tub folliculitis”)Yeasts (candida and pityrosporum)

What is the treatment?

Topical antiseptics such as Chlorhexidine Topical antibiotics, such as Fusidic acid or

Mupirocin More resistant cases may need oral

antibioics such as Flucloxacillin Hot tub folliculitis – ciprofloxacin2

Gram negative – trimethoprim

What is the most common causative organsism?

Streptococcus – Group A Strep Pyogenes.Others include Group B, C, D strep,

Staphylococcus Aureus, haemophilus influenzae (children) and anaerobic bacteria

(e.g Pasteurella spp. After animal bites)

Oral Flucloxacillin or erythromycin if allergic

Co-amoxiclav in facial cellulitis If severe systemic upset, may require

admission for IV antibiotics. After the acute attack has settled,

especially in recurrent episodes – consider the underlying cause

Painful red nodule

Deeper Staphylococcal abscess of the hair follicle

Coalescence of boils leads to the formation of a carbuncle

Treatment is with systemic antibiotics and may need incision and drainage.

Consider looking for underlying causes, such as diabetes