CH 21 : Microbial Diseases of Skin Flashcards
What is a vesicle
small fluid-filled lesions
What is a bullae
larger fluid-filled lesions (> 1 cm in diameter)
What is a macule
flat lesions (often reddish)
what is a Papule
raised lesions
What types of skin lesions can be seen?
- Vesicles: small fluid-filled lesions
- Bullae: larger fluid-filled lesions (> 1 cm in diameter)
- Macules: flat lesions (often reddish)
- Papules: raised lesions
- When they contain pus: Pustules
When does a vesicle become a bulla?
if such a lesion is greater than 0.5 cm, it is termed a bulla.
What is a carbuncle?
hard round deep inflammation of tissue under the skin
- Exhibits symptoms of fever
What is a furuncle?
(boil): abscess, localized region of pus surrounded by inflamed tissue
- Antibiotics do not penetrate well into abscesses
Which Gram + bacterium causes inflammatory acne?
Propionibacterium acnes (Cutibacterium)
what are comedos?
whiteheads
What are comedones?
blackheads
What is a virulence factor?
characteristic or structure that contrutues to the ability of a microbe to cause disease
What are the names of the toxins that cause scalded skin syndrome?
- Caused by Staphylococcus toxin
- Exfoliative toxin A- localized
- Exfoliative toxin B-distant sites
- Cause a separation of skin layers
Which two bacteria cause impetigo?
Streptococcus pyogenes
Staphylococcus aureus
How does TSST-1 affect the body?
Toxins forms at growth site and circulates in bloodstream (TSS)
Cause fever, headache, vomiting, vascular shock
what organism causes toxic shock syndrome?
gram + bacteria; Staphylococcus aureus
what is erysipelas?
reddish patches with raised margins (can be local and systemic)
what type of bacteria cause erysipelas?
Streptococcus pyogenes
Group A beta strep (GAS)
Which organic acid produced by fermenting bacteria causes inflammation in the skin?
Propionic acid
- metabolizes sebum, eats glycerol and leaves fatty acids behind causing inflammatory acne
Which type of acne is the most severe?
Nodular cystic acne
What is the basis for subdividing
Streptococcus into smaller divisions?
Alpha - some hemolysin activity
Beta - Strong hemolysin activity
Gama - No hemolysin activity
Why are the Group A β Strep relevant?
Group A beta (aka: GAS) can fully lyse RBC so they are most commonly associated with human disease (most common human pathogens)
In what groups of people does Group B β Strep mainly cause disease?
- Newborn babies (can be passed during childbirth b/c mom has it apart of their microbiome)
- Pregnant women
- Elderly
- Immunosuppressed people
What are the toxins that contribute to necrotizing fasciitis?
pyrogenic toxins,
Exfoliative toxins A and B are released from Staphylococcus aureus (causing scalded skin syndrome)
Which bacterium is associated with water and can cause problems with
swimmers or bathers?
Pseudomonas aeruginosa
- cause Pseudomonas dermatitis (rash) b/c pores open up in warm water and bodies make the water alkaline allowing bacteria to flourish and then invade
How does measles spread?
Spread by the respiratory route
What is the approximation incubation period of measles? (rubeola and rubella)
Rubeola - About 10 days
Rubella (Togaviridae) = German measles 2 to 3 weeks
How does the chicken pox rash change over time?
First 3-4 days cause just vesicles
Then vesicles fill with pus and rupture forming scabs
how does an adult with shingles give chicken pox to a child?
chicken pox and singles are caused by the same virus (Varicella-Zoster Virus) but chicken pox is due to the initial infection, and shingles is due to virus being reactivated within the body
Can an adult with shingles give chicken pox to a child?
Yes
Are the viruses present in the body continually between chicken pox and shingles?
Yes, they remain latent within the host’s cells peripheral nerves
Which form of herpes simplex most commonly manifests near the mouth?
HSV-1
How is oral herpes usually spread?
By salvia
ex: kissing, sharing drinks, eating utensils
Which type of herpes simplex is much more common?
HSV-1
Where does herpes simplex type-2 show lesions?
Genitalia
How do superficial mycoses obtain nutrients?
Grows on keratin
Which fungi affects hair, skin and nails?
Trichophyton
Which fungi infects only the hair or skin?
Microsporum
Which fungi infects only skin and nails?
Epidermophyton
What are some genera of fungi that can infect the skin?
- Trichophyton: infect hair, skin, nails
- Microsporum: infects only the hair or skin
- Epidermophyton: affects only skin and nails
Which ringworm is of the scalp?
Tinea capitis
Which ringworm is of the foot? aka Athlete’s foot
Tinea pedis
Which ringworm is of the fingernails and toenails?
Tinea unguium
Which ringworm is of the groin? aka jock itch
Tinea cruri
What are the two skin parasites discussed in lecture?
Sarcoptes scabiei: scabies
Pediculus humanus : lice
How are skin parasites usually transmitted to a new host?
1 way of transmission would be direct contact,
What are the two subspecies of body lice?
Pediculus humanus capitis: head louse
Pediculus humanus corporis: body louse
Which subspecies of lice can transmit disease?
Pediculus humanus corporis: body louse
what is Necrotizing fascilitis? what organism causes it?
Streptococcus pyogenes
Group A beta strep (GAS)
“flesh eating bacteria” causes extreme swelling and destruction of skin
what bacteria is associated with GBS? what does it stand for?
Group B beta strep
Streptococcus agalactiae
what are the three types of acne in order of increasing severity?
- comedonal (mild) - white/blackheads
- inflammatory (moderate)
- nodular cystic acne (severe)
what type of organism causes folliculitis?
bacteria; Staphylococcus aureus
what causes S. aureus to infect to cause folliculitis?
enters through a natural opening in the skin (hair follicle)
what 4 things can folliculitis appear on the skin as?
pimples
sty
furuncle
carbuncle
what is a sty?
infected follicle of an eyelash
What is a raised skin lesion called?
Papule
What virus causes chickenpox? What is it called when this virus gets activated again?
Vicerella. Shingles onces its activated again
