6 bacterial infections of the skin

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2. IntroductionIntroduction Infections with pyogenic (pus forming) bacteria usually Staphylococcus aureus and/or Streptococci (usually Group A haemolytic Streptococci - GABS) 3. Factors in development of bacterial skin infection 1) the portal of entry 2) the host defences 3) the pathogenic properties of the organism 4. Classification - primary infections (pyodermas) - secondary infections 5. Primary infections (pyodermas) infections that are produced by the invasion of normal skin by a single species of pathogenic bacteria 6. Secondary infections Infections after the integrity of the skin has been broken, or the local immune milieu is altered by the primary skin condition AD, scabies, tinea, may show mixture of organisms 7. Staphylococcus - Commonly carried in nose(35%), perineum (20%), axillae and toe webs (5-10%) - Staphylococcus causes impetigo, folliculitis, and carbuncles plus deeper infections. - Staph. toxins (epidermolytic) cause bullous impetigo and SSSS( Staphylococcal scalded skin syndrome). 8. Streptococcus -- Rarely found on normal skin, often in throat (10%),occasionally in nose - Main pathogenic type Lancefield Group A. - Causes cellulitis, lymphangitis, regional lymphadenitis - Post streptococcal state (1-3 weeks later) can produce acute GN, rheumatic fever, rheumatism, erythema nodosum, psoriasis. 9. Normal FloraNormal Flora organisms that characteristically survive and multiply in various ecologic niches of the skin S. epidermidis is the principal staphylococcal species Candida Malasazia furfur , propionbacterium acne 10. Superficial Cutaneous infectionsSuperficial Cutaneous infections Impetigo infections in the epidermis Untreated pyodermas can extend to the dermis, resulting in ecthyma 11. Two clinical patterns Bullous impetigo and Nonbullous impetigo 12. Non-Bullous Impetigo 70% of impetigo industrialized countries -- S. aureus and less often by group A streptococcus in developing countries group A streptococcus remains a common cause Occurs in children of all ages and adults usually spreads from nose to normal skin 13. Cutaneous Lesions initially a transient vesicle or pustule honey-colored crusted plaque Sunounding erythem 90% of prolonged,untreated regional LAP May progress to Ecthyma 14. Bullous Impetigo by phage group II S. aureu Three types of eruptions 1) bullous impetigo, 2) exfoliative disease( SSSS) 3) staphylococcal Scarlet fever Extracellular exfoliative toxins ("exfoliatin") types A and B 15. Cutaneous lesions more common in newborns and infants rapid progression of vesicles to flaccid bullae bullae arises on normal skin fluid clear yellow- dark yellow tubid- collapse may crust 16. Laboratory Gram stain Culture Histology 17. Treatment - good hygiene removal of crusts. - Antibiotics - topical if mild - mupirocin, fusidic acid, - Systemic if severe, multiple lesions, - cloxacillin, erythromycin, amoxi+ clavulanic acid, cephalexin 18. Ecthyma usually a consequence of neglected impetigo characterized by thickly crusted erosions or ulcerations Caused by Group A Strept and/or Staph Commonest in children or debilitated adults, homeless and soldiers 19. most commonly on the lower extremities ulcer has a punched out appearance Covered with dirty greyish-yellow crust heals slowly Treat as impetigo 20. Folliculitis a pyoderma that begins within the hair follicle a small, fragile, dome-shaped pustule occurs at the infundibulum (ostium or opening) of a hair follicle 21. Children scalp Adults - beard area, axillae, extremities, and buttocks Can complicate to Furuncles if untreated 22. Furuncles boil deep-seated inflammatory nodule that develops around a hair follicle areas with friction, occlusion, and perspiration usually from a preceding, more superficial folliculitis 23. Cutaneous Lesions solitary or multiple hard, tender, red folliculocentric nodule undergoes abscess formation Ruptures 24. Carbuncle more extensive, deeper, communicating, lesion that develops when multiple, closely set furuncles coalesce. more serious inflammation red and indurated, and multiple pustules soon appear on the surface, draining externally around multiple hair follicles scar fever and malaise - ill 25. beware of bacteremia from such lesions esp when appears on the face infection such as osteomyelitis, acute endocarditis, or brain abscess recurrent furunculosis 26. Treatment a systemic antibiotic as impetigo for mild cases severe infections or infections in a dangerous areas - maximal antibiotic dosage by the parenteral route drain if abscess 27. Erysipelas caused by group A -hemolytic streptococcus acute infection of skin- level of part of dermis superficial cellulitis with marked dermal lymphatic vessel involvement face or a lower extremity superficial erythema, edema with a sharply defined margin to normal tissue 28. there may be portal of entry Recurrent erysipelas tinea pedis, lymphedema surgery Can cause lymphedema 29. Cellulitis infection extends deeper into the dermis and subcutaneous tissue S. aureus and GAS common causes looks erysipelas but lack of distinct margins, deeper edema, surface bulla/necrosis can go deep if untreated fesciitis regional LAP portal of entry evident if half of cases 30. Treatment Supportive - rest, immobilization, elevation, moist heat, analgesia. Dressings -cool sterile saline dressings for removal of purulent exudates and necrotic tissue Surgical - Drain abscess 31. Antimicrobial Therapy - against strept in erysipelas - against staph in cellulitis + /- against strept 32. THANKSTHANKS