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1. Direct infection of skin : impetigo, ecthyma, folliculitis, furunculosis, carbuncle, sycosis. 2. Secondary infection: eczema, infestations, ulcers,

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Text of 1. Direct infection of skin : impetigo, ecthyma, folliculitis, furunculosis, carbuncle, sycosis. 2....

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  • 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.
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  • Direct inf. of skin or subcut. tissue: Impetigo, ecthyma, cellulitis, vulvovaginitis, perianal inf., strepto. ulcers, blistering distal dactylitis, necrotizing fasciitis. 2 ry inf.: eczema, infestations, ulcers, etc.
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  • 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.
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  • Mechanical disruption (inflammations, abrasions) Prolonged use of steroids, topical or systemic Presence of systemic illnesses (DM, malignancy) Immunosuppression Malnutrition Anaemia
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  • Acute contagious skin infection caused mostly by staph. Aureus and strept. Affects children mainly esp. in summer times.
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  • 1- Non-bullous impetigo: Caused by staph., strept. or both organisms. 2- Bullous impetigo: Caused by staph aureus.
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  • Staph. aureus or gp A stretp. (GAS) or both mixed infections. May arise as 1 ry inf. or as 2 ry 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.
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  • 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.
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  • 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.
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  • Circinate impetigo: with peripheral extension of lesion & healing in the center.
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  • Crusted impetigo: on the scalp complicating pediculosis. Occipital & cervical LNs are usually enlarged & tender.
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  • Ecthyma (ulcerative impetigo): adherent crusts, beneath which purulent irregular ulcers occur. Healing occurs after few wks, with scarring.
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  • Site: more on distal extremities (thighs & legs).
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  • Age: all ages, but commoner in childhood & newborn (impetigo neonatorum). Site: face is often affected, but the lesions may occur anywhere, including palms & soles.
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  • 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.
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  • 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 ).
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  • 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.
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  • inflammatory disease of the hair follicles, which may be infectious or non-infectious.
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  • Superficial Folliculitis (Bockharts Impetigo)
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  • a dome-shaped pustule at the orifice of a hair follicle that heals within 7-10 days.
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  • Caused by staph aureus and affects mainly extremities and scalp. Topical steroids are a common predisposing factor.
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  • Sychosis Vulgaris
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  • 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.
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  • Pseudofolliculitis
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  • from penetration into the skin of sharp tips of shaved hairs.
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  • 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.
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  • Cellulitis is an infection of subcutaneous tissues. Ersipelas: Its 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.
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  • 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.
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  • Edge of the lesion: well demarcated and raised in erysipelas and diffuse in cellulitis.
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  • Recurrences may lead to lymphedema. Subcutaneous abscess. Septicemia. Nephritis.
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  • Systemic antibiotics, especially penicillin, e.g. benzyl penicillin 600-1200 mg IV/6 hrs or cephalosporines. Rest, analgesics.
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  • Erythrasma
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  • It is mild, chronic, localized superficial infection of skin by Coryn. Minutissimum. Clinically: sharply- defined but irregular brown, scaly patches
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  • usually localized to groins, axillae, toe clefts or may cover extensive areas of trunk & limbs. Obesity & DM may coexist. Coral red fluorescence under woods light.
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  • Topical treatment with azole antifungal agents for 2 weeks or topical fucidin. Erythromycin orally.
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  • A mother brings 5 yr old Johnny to surgery. He has developed this rash, which is weeping and crusting.
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  • What is the diagnosis?
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  • A highly infectious skin disease, which commonly occurs in children.
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  • What is the likely causative organism?
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  • The causative organism is usually Staphylococcus Aureus or can be strep pyogenes.
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  • What is the treatment?
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  • Treatment: Mild localised cases - use topical antibiotic Polyfax Widespread or more severe infections use systemic antibiotics, such as flucloxacillin (or erythromycin if penicillin allergic)
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  • 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.
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  • A 27 year old business man attends surgery complaining of pain and itching in the beard area. You examine him and see the following:
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  • What is the Diagnosis?
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  • 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.
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  • What is the causative organism?
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  • 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)
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  • What is the treatment?
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  • 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 ciprofloxacin 2 Gram negative trimethoprim
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  • What is the most common causative organsism?
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  • 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)
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  • 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
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  • Painful red nodule
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  • 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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  • Thank You