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24 Cards in this Set
- Front
- Back
Describe the structure of skin.
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Epidermis:
-Thin outer part, composed of layers of dead epithelial cells – stratum -Replaced every 25-45 days -Physical barrier against microbes Dermis: -Connective tissue; hair follicles, sweat glands, oil glands, neurons -Sebaceus glands- softens and lubricate the skin |
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Describe the normal microbiota of the skin.
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-Normally harmless, able to survive on the skin resistant to drying and high concentration of salt
-These microbes cannot be completely removed through cleansing -Those in hair follicles and sweat glands reestablish rapidly-responsible for body odor -May be opportunistic pathogens Representatives -Gr + cocci (Staphylycococcus, Micrococcus) -G+ pleomorphic rods- diphteroids; Propionibacterium acnes-anaerobic bacteria, inhabit hair follicles, produce propionic acid (maintains the acidity of the skin, pH 3-5) -The yeast, Malassezia – cause skin scaling dandruff |
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What is acne?
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-The most common skin disease caused by Propionibacterium acnes
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Why does acne happen?
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-Normally, dead cells and sebum are discharged through pores to skin surface
-Overproduction of sebum leads to clogging the pores -Propionobacterium acnes digests the oily material-fatty acids are produced -Bacterial antigens + fatty acids causes local inflammation |
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what is Staphylococcus Aureus?
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Staphylococcus Aureus
-The most pathogenic are coagulase positive (blood clot protects them against phagocytosis) -Found in hospital environments, resistant to antibiotics, difficult to treat. Staphylococcal skin infection -Staphylococci- spherical gr+ bacteria; form irregular clusters -Two groups: Coagulase “+” strains Coagulase “-“ strains -Coagulase positive strains coagulate (clots) fibrin in blood. -Coagulase negative strains make up 90% of normal microbiota. Pathogenic only when the skin is broken. (Staphylococcus epidermidis) |
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Staphylococcus Aureus causes infection of hair follices.
True or false? |
True
Causes infection of hair follicles -Folliculitis –mild superficial inflammation of hair follicles -Furuncle- more serious folliculatis -Carbuncle-extensive damage of neighboring tissue |
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Describe strettococus.
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-Spherical, Gr+ bacteria forming chains
-There are two groups of streptococci: -Beta-hemolytic: (hemolysins lyse red blood cells and other cells) -Alpha-hemolytic: (non-hemolytic) -The most important Streptococcus belongs to group A (also called Streptococcus pyogenes) |
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What is Scaled Skin Syndrome and whats is caused by?
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Scaled Skin Syndrome (peeling off the skin)- skin infection of newborns and children under age 2)
-Caused by staphylococci that were lysogenized by certain phages -Toxins (A&B) are responsible for damage -The patient is vulnerable to secondary infection |
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What are pseudomonads and what infections does it cause?
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-Aerobic, Gr- bacteria with polar flagella
-Found in water and soil -Representative- Pseudomonas aeruginosa-opportunistic pathogen -Causes dermatitis – rash, associated with swimming in pools -P. aeruginosa is a common pathogen in burn patients -Treatment: antipseudomonal Beta-lactame antibiotics |
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List the viral diseases of the skin.
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--Warts
-Smallpox (Variola) -Chickenpox (Varicella) -Herpes simplex -Measles (Rubeola) -Rubella (German measles) |
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What enables the chickenpox virus to remain latent?
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-The virus persist inside the nerve cell as viral DNA
-Not recognized by the immune system -Later the virus may be reactivated (by stress) when it moves along the nerve to skin area. -It causes a new outbreak (shingles (herpes zoster)) |
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Describe warts.
What causes it, how its transmitted and how its treated. |
-Warts
-Caused by human papillomavirus (HPV-80 types) -Common in children -In 70% of cases disappear on their own -Transmitted by -contact - sexual contact- genital warts -respiratory routs -Treated by -Liquid nitrogen (very low temp), electrical current, burning with acids, laser treatment |
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Describe Smallpox (Variola)
What causes it, how its transmitted and how its treated. |
-Caused by orthopoxyvirus
-Two forms: Variola major- mortality 20 % Variola minor-mortality less than 1% -Transmitted by the respiratory route and contact -Symptoms: skin lesions; postules after 10 days -The first vaccine- the one against smallpox -Incubation period: 12 to 14 days -Treatment: immediate vaccination -The first disease that was eradicated -Prevention: Vaccination was discontinued in 1972 |
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Describe chickenpox (Varicella)
What causes it, how its transmitted and how its treated. |
-A mild childhood disease.
Mortality rate is very low -The disease is caused by herpesviruse varicella-zoster (human herpesvirus 3) -Acquired through respiratory droplets or fluid of active skin lesions -Skin lesions manifest the disease -Virus moves from the skin to nerve cell near the spine -There it remains latent -Self-limiting |
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Describe herpes simplex.
- What are the two types |
-Two groups: HSV-1 and HSV- 2
Herpes simplex virus type 1 -Infection is manifested with lesions in the oral mucous membrane- “cold sores” or “fever blisters” -90% of population infected- many subclinical Type 1- The virus is latent in the nerve that communicates between face and central and nerve system (trigeminal nerve) -Sunburn, emotional stress and hormonal changes can cause reappearance of the infection Type 2- genital herpes -Can be differentiated from HSV-1 by its antigenic makeup -Transmitted by sexual contact -Latent in the sacral nerve ganglia |
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Describe Measles (Rubeola)
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-Acquired by the respiratory route
-Symptoms similar to common cold, rash on the face and trunk, lesions in the mouth -Complications-pneumonia, encephalitis -The law requires vaccination for school children- not earlier -Dangerous disease for very young and very old people |
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Describe Rubella (German measles)
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-A mild viral disease
-Manifestation-light fever, small red spots -If contracted by pregnant woman a fetal damage is possible (deafness, heart defects, mental retardation) -Rubella is prevented by effective vaccine (not recommended for pregnant women) |
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List and describe the fungal diseases of the skin.
- What its caused by, treatments. |
-Dermatomycoses – fungal infection of skin, nails, hair (keratin) :
– ringworm -Can digest keratin -Transmitted by contact with fomites (non living objects) -Ringworm of the groin – tinea cruris -Ringworm of the feet- tina pedis- athlete’s foot -Ringworm of the scalp- tina capitis Candidiasis: -Infection caused by the yeast Candida albicans -C. albicans can overgrow the mucosal tissue when the normal microflora is suppressed (antibiotic treatment) -In newborn infants, whitish overgrowth in the mouth cavity -Treatment- miconazole, nistatin |
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List the microbial diseases of the eye.
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-Conjunctivitis
-Trachoma |
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Describe Conjunctivitis
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Conjunctivitis (red eye)- inflammation of conjunctiva (mucous membrane that lines the eyelids and covers the eye ball)
-Can be caused by bacteria or viruses -Bacterial conjunctivitis is caused by Heamiphilus influenza and Pseudomonas -Source of infection- skin, upper respiratory tract and contact lenses |
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Describe trachoma.
_cause _Symptoms _ Treatment |
-Infectious disease caused by Chlamidia trachomitis (intracellular parasite)
-The most often cause of blindness -C. trachimatis –causes conjunctivitis – thicken the upper eyelid -Mechanical damage of cornea caused by in turning of eyelashes -Treatment- tetracycline |
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What bacteria is found on skin, that is salt tolerant and produces antimicrobial substances that maintain balance?
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Staphylococci Epidermidis
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What term means 'pus' 'generating'?
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Pyogenic
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What are two causes of Pyogenic Infections
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Staphylococcus aureus
Streptococcus pyogenes |