Diseases of the Skin Flashcards
Chapter 21
What is an important physical barrier to infections?
Intact Skin
What are other important physical barriers to infections? (3)
- Epidermis
- Mucous Membranes
- Eyes
(T/F) Eyes have normal flora
False
What causes infections? (4)
- bacteria
- viruses
- fungi
- parasites
What two bacteria cause the most common superficial skin infections?
- Staphylococcal
- Streptococcus
Is normal flora Gram (+) or Gram (-) ?
Primarily Gram (+)
Give examples of Normal Flora (5):
- Staphylococcus
- Micrococcus
- Diptheroids
- Propionibacterium acnes
- Corynebacterium xerosis
Describe Diptheroids (2):
- Gram (+)
- Pleomorphic rods
What does pleomorphic mean?
Can change shape and size
What on the skin contains nutrients? (2)
- perspiration
- sebum
What on the skin inhibits microbes/pathogens? (2)
- salt
- fatty acids (some)
What does lysozyme do?
Hydrolyzes peptidoglycan
Define Vesicles:
Small, fluid-filled lesions
Define Bullae:
Vesicles larger than 1 cm in diameter
Define Macules:
Flat, reddened lesions
Define Papules:
Raised Lesions
Define Pustules
Raised lesions with pus
Define Exanthem:
Skin rash arising from a disease
Define Enanthem:
Rash on mucous membranes arising from a disease
Describe Staphylococcal Infections (2):
- Gram +
- coccus (grape-like clusters)
What virulence factors do Staphylococcal Infections have? (5)
- Coagulase
- Leukocidin
- Exfoliative Exotoxins
- Enterotoxins
- Toxic Shock Syndrome Toxin
What does Coagulase do?
Clots blood plasma (protects against phagocytosis)
What does Coagulase protects pathogens from?
Phagocytosis
What does Leukocidin do?
Destroys phagocytes
What does Exfoliative Exotoxins do?
Cause Scalded Skin Syndrome (SSS)
What do Enterotoxins cause?
Food Poisoning (Later)
Describe Staphylococcus aureus (2):
- (Most) Coagulase Positive
- (Most) Pathogenic
How does Staphylococcus aureus enter the body? (3)
- nasal passages
- hair follicles
- skin abrasions (enters blood)
What diseases does Staphylococcus aureus cause? (5)
- Folliculitis
- Boils
- Sty
- Carbuncles
- Impetigo
What is Folliculitis?
Pimples, pustules
What are other names for boils? (2)
- Furuncles
- Abscesses
What are Boils?
Deeper, pus-filled infection
What are Stys?
Infection at base of an eyelash
What are Carbuncles?
Deeper infection, progressively invasive
Describe Carbuncles (4):
- usually encapsulated
- no circulation
- many are MRSA (methicillin resistant)
- harder to treat
What is Impetigo?
Highly contagious, crusty lesions
Describe Toxic Shock Syndrome (3)
- life threatening
- occurs in menstruating women (highly absorbent tampons)
- strain that produces and exotoxin (TSST-1)
What are the Symptoms of Toxic Shock Syndrome? (6)
- fever
- sun burn rash
- vomiting
- decreases in blood pressure (leads to…)
- shock
- death
Describe Staphylococcus epidermidis (2):
- coagulase negative strain
- mainly normal flora
Describe Streptococcal Infections (3):
- gram (+)
- coccus (grows in chains)
- divided into 3 groups (hemolysins)
What are the three hemolysins? (3)
- Alpha
- Beta
- Gamma
Describe Alpha Hemolytic:
Partial RBC breakdown
Describe Beta Hemolytic:
Complete RBC breakdown
Describe Gamma Hemolytic:
No RBC breakdown
Which hemolysin is the most pathogenic?
Beta Hemolytic
What are Beta Hemolytic further divided into?
Groups A-T
Which Beta Hemolytic Group causes the most disease?
Group A Streptococci (GAS)
What is an example of a Group A Streptococci (GAS)?
Streptococci pyogenes
What differentiates S. pyogenes?
M Protein
What are the virulence factors of Streptococcal Infections? (8)
- Hemolysins
- M Protein
- Erythrogenic toxin
- DNAse
- Streptokinase
- Hyaluronidase
- Leukocidins
- Capsules
What known diseases are Streptococcal Infections? (3)
- Erysipelas
- Impetigo
- Necrotizing fasciitis
Describe Necrotizing Fasciitis (5)
- Group A Streptococci (Beta Hemolytic)
- Streptococcus pyogenes
- Highly invasive infection
- Strains produce enzymes
- Reach deeper tissues (damage/destroy muscles)
In simple terms, what is Necrotizing Fasciitis?
Flesh eating bacteria
What enzymes do strains of Necrotizing Fasciitis produce? (3)
- hyaluronidase
- protease
- streptokinase
How is Necrotizing Fasciitis treated? (2)
- Surgical removal of infected tissues
- IV antibiotic therapy
What are examples of Viral Skin Diseases? (6)
- German Measles (Rubella)
- Measles (Rubeola)
- Chickenpox & Shingles
- Smallpox
- Warts (HPV)
- Herpes Simplex
Describe Warts (3):
- Human papilloma virus (HPV)
- Most are benign skin tumors
- Found on fingers, larynx, genitals
Describe the Human Papilloma Virus (3):
- Double Stranded
- DNA
- Non-enveloped
How is HPV spread? (2)
Direct Contact
- Humans or Fomites
- Sexually Transmitted (Genital Warts)
How is HPV treated? (3)
- Freezing (liquid nitrogen)
- Burning (Acids)
- Laser Therapy
Describe Smallpox (4):
- Poxviridae
- Double stranded
- DNA
- Enveloped
What are the two forms of Poxviridae?
- Variola Major (20% die)
- Variola Minor (~1% die)
How is smallpox spread?
Respiratory route -> Blood -> Skin
How many incubation days for smallpox?
12 days
What cells does smallpox infect? (3)
- phagocytic cells
- blood cells
- skin (face then trunk)
What is a systemic infection?
One in the bloodstream
What is viremia?
Virus in the bloodstream
When was smallpox eradicated?
1980
How was smallpox eradicated? (2)
- vaccination (live attenuated vaccine)
- humans are only carriers (reservoir)
What virus causes chickenpox?
Varicella
What virus cases shingles?
Zoster
Describe Chickenpox & Shingles (4):
- Highly Contagious
- may remain in a latent stage
- causes small, irregular skin lesions
- Varicella-Zoster
Describe Varicella-Zoster Virus (3):
- Double Stranded
- DNA
- Enveloped
How are Chickenpox and Shingles spread?
Respiratory Route -> Blood -> Skin
How many incubation days for Chickenpox & Shingles?
14-16 days
Where are Chickenpox & Shingles latent in?
Dorsal root ganglion
What is shingles the result of?
Reactivation of Latent VZV
Can someone who’s never had chickenpox get shingles?
No! You can only get shingles if you have had chickenpox beforehand
What reactivates Chickenpox/Shingles? (2)
- stress
- immune deficiency
What are treatments for Chickenpox/Shingles?
Acyclovir
What vaccines are available for Chickenpox/Shingles? (2)
- Varivax
- Shingrex
Describe the Varivax Vaccine (2):
- Attenuated Live
- Recommended for young children (12-24 months)
Describe the Shingrex Vaccine (2):
- subunit vaccine (parts of viral envelope)
- over 50 years
- prevents shingles
Describe Measles (Rubeola) (5):
- Highly Contagious
- Paramyxoviridae
- Humans are the only reservoir
- Macular Skin Rash (face -> trunk)
- Koplik’s Spots
Describe Paramyxoviridae
- (-) RNA
- Enveloped
How are Measles (Rubeola) spread?
Respiratory Route
How many incubation days for Measles (Rubeola)?
10-12 days
What are the symptoms for measles? (3)
- Runny Nose
- Fever
- Sore Throat
What are Koplik’s Spots?
Small, raised, red spots with white center on oral mucosa
Where are Koplik’s Spots found?
On oral mucosa
What complications occur with Rubeola?
Ear infections - Severe Pneumonia
What form of measles is fatal?
Subacute Sclerosing Panencephalitis (SSPE)
How common is SSPE?
Very Rare
What vaccines are there for Rubeola?
MMR (measles mumps rubeola) vaccine
Describe the MMR Vaccine (3):
- 1963
- live attenuated vaccine
- given at 15-18 months of age
Describe Rubella (German Measles) (3):
- Togaviridae
- Mild
- Skin Rash
Describe Togaviridae (3):
- (+) RNA
- Enveloped
- Causes Exanthema
What is Exanthema?
Skin Rash
How is Rubella spread?
Respiratory Route -> Skin
How long is the incubation period for German Measles?
2-3 weeks
What does Rubella cause?
Small macular rash (not raised) with fever
What complications can occur with Rubella?
Encephalitis (may be fatal)
When can complications with Rubella occur?
First trimester of pregnancy (Congenital Rubella)
What is Congenital Rubella?
Maternal infection with Rubella Virus during pregnancy
What vaccine is there for German Measles?
MMR Vaccine
What does Congenital Rubella Syndrome cause? (2)
- Severe Fetal Damage
- Death
How can Congenital Rubella be prevented?
Through Vaccination