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
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