CAS BI 114 Lecture Notes - Lecture 14: Lysosome, Papule, Lactobacillus
30 Apr 2018
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Infectious Diseases of the Skin
Three Layers
•1. Epidermis - top layer, composed of layers of tightly packed cells
•very top layers = dead skin cells (20-30 layers)
•Has a robust microbiome
•2. Dermis
•3. Hypodermis
The Skin Environment
•Top surface is densely-packed dead cells
•Two secretions added daily
•1. Sebum (oil) from sebaceous glands - high lipid content
but low pH (acidic)
•Lipid breakdown products are toxic to some bacteria
•2. Sweat from sweat glands
•Contains lysozome
•High salt content and low pH (acidic)
•Some structures permit through all three layers
•Sweat glands - low pH & high saltiness
•Oils - low pH which makes the skin an inhospitable location
for pathogens
Normal Microbiota
•Bacteria, fungi, short-lasting viruses
•Bacterial populations - staphylococcus and streptococcus
predominant while others are present such as Pseudomonas
and Lactobacillus
•Individual and region variation
•Fungal populations includes Candida and others
Lesions
•Lesion - any individual patch of disease
•Types of Lesions:
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•Vesicle - raised, clear fluid-filled patch
•Pustule - raised, pus-filled patch
•Macule - flat, discolored and smooth (not raised or raised slightly) patch
•Papule - raised, solid and not fluid filled patch
Rashes
•Rashes - more than one lesion affecting an area
•Types of Rashes:
•Vesicular - raised, fluid-filled lesion
•Papular Rash - raised, solid lesion
•Maculopapular Rash - small, slightly raised bumps or a mix of raised with fluid & not raised rashes
•Flaking Rashes
Viral Infections of the Skin
•1. Varicella-Zoster Virus - causes Chicken Pox (and possibly Shingles later on)
•Respiratory illness
•Very contagious
•Systemic infection (affects multiple organs/sites)
•***Nervous System/Ocular System are Immuno-privileged - where the immune system is not
protected and thus cannot defend the body, very hard to detect in these locations
•Treatment & Prevention
•Treatment - none
•Prevention - vaccines that can be taken after 1 and alternate vaccines for shingles prevention
•2.
Variola Virus - causes Small Pox
•Last known case in America was in 1949
•Virus does still exist in research labs (controlled by two world governments)
•Vaccines are given for certain populations
•Symptoms - high fever, lesions first appear in mouth before spreading everywhere, after 2 weeks
these lesions crust over
•Can cause permanent scarring and possibly death
•3. Measles Virus - causes Measles
•4. Herpes Simplex Virus-1 - causes Cold Sores/Oral Herpes
•Transmitted through saliva or indirect contact (ex: through towels, sheets)
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Document Summary
Epidermis - top layer, composed of layers of tightly packed cells: very top layers = dead skin cells (20-30 layers, has a robust microbiome, 2. The skin environment: top surface is densely-packed dead cells, two secretions added daily, 1. Sebum (oil) from sebaceous glands - high lipid content but low ph (acidic: lipid breakdown products are toxic to some bacteria, 2. Normal microbiota: bacteria, fungi, short-lasting viruses, bacterial populations - staphylococcus and streptococcus predominant while others are present such as pseudomonas and lactobacillus, individual and region variation, fungal populations includes candida and others. Propionibacterium acnes (p. acnes: causes acne/pimples, likes lipids (can digest them and use them as a food source, drawn towards hair follicles where they accumulate until the pore is closed over, 2. Streptococcus pyogenes (s. pyogenes: causes strep throat, expresses an acid that digests away skin cell layers, can cause flesh-eating and penetrating infections, 4.
