Bacterial skin infection- dermatology
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Transcript of Bacterial skin infection- dermatology
BACTERIAL SKIN INFECTION
KUSHAL KUMAR
BACTERIAL INFECTION OF SKINThe SkinDefinition
Skin is largest organ of body. It protects underlying tissues and organs, protects body from mechanical injury, and ultraviolet rays of sun.
SKIN INFECTIONS
• The skin always has some amount of bacteria, fungus and viruses living on it.
• Occur when there are breaks in the skin and the organisms have uncontrolled growth
Staph. Aureus Infection
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.
Strepto. Infection(gp A streptococci)
Direct inf. of skin or subcut. tissue: Impetigo, ecthyma, cellulitis, vulvovaginitis, perianal inf., ulcers, blistering, 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
IMPETIGO
•Acute contagious skin infection caused mostly by staph. Aureus and strept.
•Affects children mainly, esp. in summer times.
CLINICAL TYPES
•1- Non-bullous impetigo: • Caused by staph., strept. or both organisms.
•2- Bullous impetigo:• Caused by staph aureus.
NON-BULLOUS IMPETIGO
• Staph. aureus or gp A stretp. 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 .Any part could be affected except palms & soles.
Complications: Post-streptococcal acute glomerulo-nephritis “AGN” especially in cases due to strepto. pyogenes
VARITIES:
• Circinate impetigo: with
peripheral extension of
lesion & healing in the
center.
•Crusted impetigo: • on the scalp complicating
pediculosis. Occipital & cervical Lymph nodes are usually enlarged & tender.
• Ecthyma (ulcerative
impetigo): adherent crusts,
beneath which purulent
irregular ulcers occur. Healing
occurs after few weeks, with
scarring.
• Site: more on distal extremities (thighs & legs).
BULLOUS IMPETIGO
• 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.
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BULLOUS IMPETIGO
•
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BULLOUS IMPETIGO
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BULLOUS IMPETIGO
TREATMENT OF IMPETIGO:
Treatment of predisposing causes: e.g. pediculosis & scabies.
Remove the crusts: by olive oil or hydrogen peroxide.
Topical antibiotic: e.g. tetracycline, gentamycin,
FOLLICULITIS
• 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.
PSEUDOFOLLICULITIS
• from penetration into the skin of sharp tips of shaved hairs.
FRUNCULOSIS (BOILS)
• It is a staphylococcal infection , 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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FURUNCLE
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FURUNCLE / CARBUNCLE
CELLULITIS & ERYSIPELAS
•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 cellulitis.
Erythema, heat, swelling and pain or tenderness.
Fever and malaise which is more severe in erysipelas.
In erysipelas: blistering and hemorrhage.
Lymphadenopathy are frequent.
• Edge of the lesion: well demarcated and raised in erysipelas and diffuse in cellulitis.
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CELLULITIS
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CELLULITIS
COMPLICATIONS
• Recurrences may lead to lymphedema.
• Subcutaneous abscess.
• Septicemia.
• Nephritis.
TREATMENT
• Systemic antibiotics, especially penicillin, e.g. benzyl
penicillin (600-1200 mg IV/6 hrs)
• Rest, analgesics.
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ERYSIPELAS
SKIN DISEASES RELATED TO CORYNEFORM BACTERIA
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.
TREATMENT
• Topical treatment with azole antifungal agents for 2 weeks
or topical fucidin.
• Erythromycin orally.
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