CH 21 : Microbial Diseases of Skin

Question 1

What is a vesicle

Answer 1

small fluid-filled lesions

Question 2

What is a bullae

Answer 2

larger fluid-filled lesions (> 1 cm in diameter)

Question 3

What is a macule

Answer 3

flat lesions (often reddish)

Question 4

what is a Papule

Answer 4

raised lesions

Question 5

What types of skin lesions can be seen?

Answer 5

1. Vesicles: small fluid-filled lesions
2. Bullae: larger fluid-filled lesions (> 1 cm in diameter)
3. Macules: flat lesions (often reddish)
4. Papules: raised lesions
   - When they contain pus: Pustules

Question 6

When does a vesicle become a bulla?

Answer 6

if such a lesion is greater than 0.5 cm, it is termed a bulla.

Question 7

What is a carbuncle?

Answer 7

hard round deep inflammation of tissue under the skin

• Exhibits symptoms of fever

Question 8

What is a furuncle?

Answer 8

(boil): abscess, localized region of pus surrounded by inflamed tissue

• Antibiotics do not penetrate well into abscesses

Question 9

Which Gram + bacterium causes inflammatory acne?

Answer 9

Propionibacterium acnes (Cutibacterium)

Question 10

what are comedos?

Answer 10

whiteheads

Question 11

What are comedones?

Answer 11

blackheads

Question 12

What is a virulence factor?

Answer 12

characteristic or structure that contrutues to the ability of a microbe to cause disease

Question 13

What are the names of the toxins that cause scalded skin syndrome?

Answer 13

• Caused by Staphylococcus toxin

2. Exfoliative toxin A- localized
3. Exfoliative toxin B-distant sites

• Cause a separation of skin layers

Question 14

Which two bacteria cause impetigo?

Answer 14

Streptococcus pyogenes
Staphylococcus aureus

Question 15

How does TSST-1 affect the body?

Answer 15

Toxins forms at growth site and circulates in bloodstream (TSS)

Cause fever, headache, vomiting, vascular shock

Question 16

what organism causes toxic shock syndrome?

Answer 16

gram + bacteria; Staphylococcus aureus

Question 17

what is erysipelas?

Answer 17

reddish patches with raised margins (can be local and systemic)

Question 18

what type of bacteria cause erysipelas?

Answer 18

Streptococcus pyogenes
Group A beta strep (GAS)

Question 19

Which organic acid produced by fermenting bacteria causes inflammation in the skin?

Answer 19

Propionic acid
- metabolizes sebum, eats glycerol and leaves fatty acids behind causing inflammatory acne

Question 20

Which type of acne is the most severe?

Answer 20

Nodular cystic acne

Question 21

What is the basis for subdividing
Streptococcus into smaller divisions?

Answer 21

Alpha - some hemolysin activity

Beta - Strong hemolysin activity

Gama - No hemolysin activity

Question 22

Why are the Group A β Strep relevant?

Answer 22

Group A beta (aka: GAS) can fully lyse RBC so they are most commonly associated with human disease (most common human pathogens)

Question 23

In what groups of people does Group B β Strep mainly cause disease?

Answer 23

• Newborn babies (can be passed during childbirth b/c mom has it apart of their microbiome)
• Pregnant women
• Elderly
• Immunosuppressed people

Question 24

What are the toxins that contribute to necrotizing fasciitis?

Answer 24

pyrogenic toxins,
Exfoliative toxins A and B are released from Staphylococcus aureus (causing scalded skin syndrome)

Question 25

Which bacterium is associated with water and can cause problems with swimmers or bathers?

Answer 25

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

Question 26

How does measles spread?

Answer 26

Spread by the respiratory route

Question 27

What is the approximation incubation period of measles? (rubeola and rubella)

Answer 27

Rubeola - About 10 days Rubella (Togaviridae) = German measles 2 to 3 weeks

Question 28

How does the chicken pox rash change over time?

Answer 28

First 3-4 days cause just vesicles Then vesicles fill with pus and rupture forming scabs

Question 29

how does an adult with shingles give chicken pox to a child?

Answer 29

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

Question 30

Can an adult with shingles give chicken pox to a child?

Answer 30

Yes

Question 31

Are the viruses present in the body continually between chicken pox and shingles?

Answer 31

Yes, they remain latent within the host’s cells peripheral nerves

Question 32

Which form of herpes simplex most commonly manifests near the mouth?

Answer 32

HSV-1

Question 33

How is oral herpes usually spread?

Answer 33

By salvia ex: kissing, sharing drinks, eating utensils

Question 34

Which type of herpes simplex is much more common?

Answer 34

HSV-1

Question 35

Where does herpes simplex type-2 show lesions?

Answer 35

Genitalia

Question 36

How do superficial mycoses obtain nutrients?

Answer 36

Grows on keratin

Question 37

Which fungi affects hair, skin and nails?

Answer 37

Trichophyton

Question 38

Which fungi infects only the hair or skin?

Answer 38

Microsporum

Question 39

Which fungi infects only skin and nails?

Answer 39

Epidermophyton

Question 40

What are some genera of fungi that can infect the skin?

Answer 40

- Trichophyton: infect hair, skin, nails - Microsporum: infects only the hair or skin - Epidermophyton: affects only skin and nails

Question 41

Which ringworm is of the scalp?

Answer 41

Tinea capitis

Question 42

Which ringworm is of the foot? aka Athlete’s foot

Answer 42

Tinea pedis

Question 43

Which ringworm is of the fingernails and toenails?

Answer 43

Tinea unguium

Question 44

Which ringworm is of the groin? aka jock itch

Answer 44

Tinea cruri

Question 45

What are the two skin parasites discussed in lecture?

Answer 45

Sarcoptes scabiei: scabies Pediculus humanus : lice

Question 46

How are skin parasites usually transmitted to a new host?

Answer 46

#1 way of transmission would be direct contact, #2 way of transmission would be via fomites (sheets etc.)

Question 47

What are the two subspecies of body lice?

Answer 47

Pediculus humanus capitis: head louse Pediculus humanus corporis: body louse

Question 48

Which subspecies of lice can transmit disease?

Answer 48

Pediculus humanus corporis: body louse

Question 49

what is Necrotizing fascilitis? what organism causes it?

Answer 49

Streptococcus pyogenes Group A beta strep (GAS) “flesh eating bacteria” causes extreme swelling and destruction of skin

Question 50

what bacteria is associated with GBS? what does it stand for?

Answer 50

Group B beta strep Streptococcus agalactiae

Question 51

what are the three types of acne in order of increasing severity?

Answer 51

- comedonal (mild) - white/blackheads - inflammatory (moderate) - nodular cystic acne (severe)

Question 52

what type of organism causes folliculitis?

Answer 52

bacteria; Staphylococcus aureus

Question 53

what causes S. aureus to infect to cause folliculitis?

Answer 53

enters through a natural opening in the skin (hair follicle)

Question 54

what 4 things can folliculitis appear on the skin as?

Answer 54

pimples sty furuncle carbuncle

Question 55

what is a sty?

Answer 55

infected follicle of an eyelash

Question 56

What is a raised skin lesion called?

Answer 56

Papule

Question 57

What virus causes chickenpox? What is it called when this virus gets activated again?

Answer 57

Vicerella. Shingles onces its activated again