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Pyoderma.pptx
- 2. INTYODRUCTION Skin is largest organ of body Maintains homeostasis, protects underlying tissues and organs, protects body from mechanical injury, microbial , damaging substances, and ultraviolet rays of sun. 2
- 3. • In immunocompetent patients, streptococci and staphylococci cause the majority of skin infections, producing a spectrum of skin lesions ranging from common to rare . 3
- 4. NORMAL HUMAN SKIN • Colonized soon after birth by a large number of bacteria that live as commensals on the epidermis and epidermal appendages. 4
- 5. Normal skin flora classification organisms location Aerobic cocci Staphylococcus aureus** S. saprophyticus S. epidermidis Micrococcus luteus All body sites, especially intertriginous areas Coryneform aerobes Corynebacterium minutissimum C. lipophilicus C. xerois Brevibacterium epidermidis intertriginous areas (axillae, inguinal, toe web) Anaerobic corynebacterium Propionibacterium acnes P. granulosum P. avidum Sebaceous glands, follicles Gram negative bacteria Acinebacter spp. Axilla, inguinal, arm pits Yeasts Malassezia furfur Sebaceous glands- rich areas (scalp) 5
- 6. The role of the normal flora • PREVENT SKIN INFECTIONS –by providing ecological competition for pathogenic microorganisms . –by hydrolyzing lipids of sebum to produce free fatty acids, which are toxic to many bacteria. 6
- 7. COMMON PYODERMAS • FOLLICULITIS is inflammation of hair follicles from Infection. • A furuncle develops when the entire follicle and surrounding tissue are involved. • A carbuncle develops When cluster of follicles involved. 7
- 8. Epidemiology →S. aureus permanently colonizes the anterior nares in 20 % of the population. 8
- 9. Etiologies • S.aureus -is the most common infectious cause of Bacterial folliculitis,Furuncle & curbuncle. 9
- 10. . PATHOGENESIS • One of the main virulence factors of S. aureus is the production of adhesins that facilitate binding to host epithelial cell surfaces. • Like as teichoic acid, lipoteichoic acid, fibronectin-binding proteins. 10
- 11. Host related factors - Pre-existing tissue injury or inflammation (surgical wound, burn, trauma) - Maceration, shaving, chronic wounds, excoriation of pruritic insect bites, and disruption of the epidermal barrier by other pathogens. - Immunosuppression, -Glucocorticoid therapy, and atopy 11
- 12. Broken skin allows Bacteria to enter 12
- 13. Unbroken skin prevents entrance of bacteria . 13
Editor's Notes
- #4: effective in the majority of bacterial skin infections, an increase in the prevalence of community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA)is a growing concern
- #6: *Whether or not S. aureus is a true resident or contaminant of the skin is a matter of controversy. However, it is commonly found in the anterior nares (3S% of population), perineum (20%), and axillae and toe webs (5-10%). IS. epidermidis is the most common coccus on human skin.
- #7: The acidic milieu which results inhibits the growth of other organisms such as Streptococcus pyogenes.
- #10: Various surface components of S. aureus, such as teichoic acid, lipoteichoic acid, fi bronectin-binding proteins, and type 5 and type 8 capsular polysaccharides, have all been implicated as substances responsible for, or contributing to, binding of the organism in the nose