Skin and SSTI Flashcards
What are some functions of the skin?
- Fluid homeostasis
- Physical protection
- Immune modulator
- Vitamin D production
- Structural/collagen
- Hot/cold regulation
- Radiation protection
- Energy storage
- Bilirubin metabolism
- Neurosensory
- AND MORE
How is a transcutaneous drug delivered?
Through the skin
Which layer of the skin is avascular, the epidermis or the dermis?
Epidermis
Does thin or thick skin have a loosely packed keratin in the stratum corneum?
Thin (face and genitals)
What are the five layers of the epidermis?
- Stratum corneum
- Stratum licidum
- Stratum granulosum
- Stratum spinosum
- Stratum basale
Where does cell division begin?
The lowest layer (stratum basale)
Which layer does keratin synthesis begin?
Stratum spinosum
What happens to cells as they move into higher layers?
They flatten, lose their nucleus and eventually die
What is the top layer of the epidermis composed of?
Stratum corneum, dead, flat skin cells
What is the function of epithelial cells of the skin?
Protective and secretory functions
What are some of the qualities of epithelial skin cells?
- Tightly packed (limited intracellular space)
- Avascular
- Highly mitotic
- Multiple layered
What are physical barriers of the skin?
- Stratum corneum provides outer layer of defense
- Tightly packed cells create a physical barrier to invasion
What are chemical barriers of the skin?
- Lysozyme (enzymatic protein in epithelial cells) degrades cell walls of bacteria (changes in this can affect skin conditions)
- Lipids act as barriers on the skin are produced in the epidermal cells (S. granulosum) these can have antimicrobial properties
What is the function of Langerhan cells in the epidermis?
They function as macrophages
*Outermost guard of the cutaneous immune system
What layer of skin is the target for transcutaneous drugs?
Subcutaneous layer (hypodermis)
What is the function of the subcutaneous layer of skin?
Insulation and cushioning
*Vascular
What do sweat glands empty onto the skins surface and where are they located?
Water and electrolytes, located in the dermis
What do sebaceous glands empty onto into hair follicles and the skins surface and where are they located?
Sebum (lipids), located in the dermis
What type of response is sweating?
Sympathetic
What is sweating mediated by?
Acetylcholine at the glandular level
What type of drug can help with hyperhydrosis?
An anticholinergic drug (blocks acetylcholine)
*Qbrexa (glycopyrronium tosylate)
What type of glands are subject to infection?
Sebaceous glands (acne)
What stimulates the secretion of sebum?
Testosterone
What initiates the development of acne?
Hyper-secretion of sebum and blocked hair follicles
What two things should be combined in treating acne?
Antimicrobials and topical retinoid (also with BP)
Should you use a topical and oral antibiotic at the same time to treat acne?
NO
What is the bacteria that causes acne?
Cutibacterium acnes
What are the two most common antibiotics for treatment of acne?
- Topical clindamycin (lincosamide)
- Oral minocycline (tetracycline)
What is the treatment for mild (comedonal) acne?
Topical Benzyol peroxide and Topical antibiotic (clindamycin)
What is the action of benzyol peroxide?
Breaks down sebum and keratin
What is the treatment for moderate (inflammatory acne)?
Topical BP, Topical retinoid, Oral antibiotic (minocycline)
What is the action of retinoic acid?
It is synthetic vitamin A which stops growth and differentiation of skin epithelial cells –> reduces sebum and keratin
What is the treatment for severe acne?
Topical BP, oral/topical antibiotic OR Isotretinoin
Why is oral isotretinoin systemic?
Because it kills epithelial cells everywhere, not just on the skin
What else can you add as a treatment for severe acne for women?
Oral contraceptives because they can reduce testosterone levels which will help reduce sebum production
What is the best drug class for C. acnes?
Oral tetracyclines
*But not for use beyond 3 months continuous
What does stimulation of a retinoic acid receptor on an epithelial cell induce?
Cellular death pathway
aka when retinoic acid binds, it kills epithelial cells
What are signs of acute inflammation?
Swollen, warm, red, painful, full of WBCs
What are signs of systemic inflammation?
Fever, malaise, anorexia, chills, sweats
Is all inflammation a infection?
NO
What causes inflammation?
Inflammatory mediators inducing WBCs
macrophages, mast cells, B and T cells, PMNs, NK cells
What do inflammatory mediators control?
- Blood vessel dilation
- Enhanced vessel wall permeability
- WBC chemotaxis
- Diapedesis
How do you differentiate between inflammation and infection?
Infection - fever, pain, hard to the touch (cellulitis)
Inflammation - no fever, itchy, soft to touch (dermatitis)
What leads inflammation due to cellulitis vs dermatitis?
Cellulitis - bacterial infection
Dermatitis - allergen, irritant or autoimmunity
What are the most common bacteria that cause of cellulitis?
- Staph aureus
- Strep pyogenes (can cause necrotizing flesh eating)
* But other organisms can also cause it
What causes cellulitis (not the bacteria)?
Skin trauma or blood borne
How do you treat cellulitis with an abscess?
- Must drain the abscess because it has no bioavailability so no drug will get to it (because it is dead cells)
- After abscess is drained, then you can treat cellulitis with a antibiotic
What are some infections that Group A Strep can cause?
- Furuncles/carbuncles
- Imeptigo
- Gangrene
Which of these bites would be the worst?
- Human
- Dog
- Cat
- Reptile
- Human is worst
- Cat
- Dog
- Reptile
