HTHSCI 2HH3 Chapter Notes - Chapter 5: Propionibacterium Acnes, Red Blood Cell, Medical Microbiology
26 May 2018
School
Department
Course
Professor
Skin and Soft Tissue Infections
Laboratory Module
Skin is not a suitable environment for microorganism colonization and growth:
• Skin’s surface does not contain sufficient amounts of moisture to sustain bacterial growth
• The secretions of the skin contain a high salt concentration and low pH
Skin can support the growth of certain microbes:
o Staphylococcus epidermis
o Corynebacterium xerosis
o Propionibacterium acnes
• Able to tolerate the dry, acidic, high salt environment characteristic of skin
• Derive nutrients from skin secretions (eg. Sebum)
Normal skin flora
Benefits the host (mutualism) by competing with pathogenic microbes for nutrients (pathogenic
antagonism), and by maintaining the low pH of the skin- both of which ultimately limit pathogenic
growth and reduce skin infection
A Physical Barrier
• Skin is mostly impermeable to microbes
• Most skin and soft tissue infections arise from exogenous penetration (trauma, surgery, bites)
• Certain microorganism (staphylococcus aureus) can penetrate skin via natural openings present
on the skin surface (sweat pores, passageway between the hair shaft and hair follicle) →
infection
Clinical Findings
Rigors: constitute shivering of the body that occurs during a high fever
Erythema: abnormal redness of the skin caused by capillary congestion, sign of infection
Raised margins: edges of a lesion that are raised compared to the normal skin surface
Hemorrhagic bullae: large, blood-filled vesicles
IV Antibiotics
Penicillin G: beta- lactam antibiotic that is effective against many bacteria that cause necrotizing
fasciitis, including group A strep
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Document Summary
Skin is not a suitable environment for microorganism colonization and growth: skin"s surface does not contain sufficient amounts of moisture to sustain bacterial growth, the secretions of the skin contain a high salt concentration and low ph. Skin can support the growth of certain microbes: staphylococcus epidermis, corynebacterium xerosis, propionibacterium acnes, able to tolerate the dry, acidic, high salt environment characteristic of skin, derive nutrients from skin secretions (eg. sebum) Benefits the host (mutualism) by competing with pathogenic microbes for nutrients (pathogenic antagonism), and by maintaining the low ph of the skin- both of which ultimately limit pathogenic growth and reduce skin infection. Rigors: constitute shivering of the body that occurs during a high fever. Erythema: abnormal redness of the skin caused by capillary congestion, sign of infection. Raised margins: edges of a lesion that are raised compared to the normal skin surface.
