Integument Microbiology

Question 1

Gram + bacteria predominate in (dry/moist) skin

Answer 1

Dry (forearm, legs, etc.)

Question 2

Gram - bacteria predominate in (dry/moist) skin

Answer 2

Moist (armpit, creases, etc.)

Question 3

Most organisms are in what layer of skin?

Answer 3

stratum corneum and upper parts of hair follicles

Question 4

Gram + microbial inhabitants of the skin

Answer 4

• Staph. epidermidis
• S. aureus
• Propionibacterium acnes
• B-hemolytic streptococci (Group A S. pyogenes & Group B S. agalactiae)
• a-hemolytic streptocci (S. viridans & S. penumoniae)

Question 5

What microbe colonizes normal skin in the nose, perineum, and vulva and commonly found on skin of patients with atopic dermatitis?

Answer 5

S. aureus

Question 6

What microbes are prevalent in areas with sebaceous glands?

Answer 6

Propionibacterium spp. (P. acnes)

Question 7

P.acnes has been renamed as

Answer 7

Cutibacterium acnes

Question 8

What microbes are rare inhabitants of skin and are inhibited by lipids

Answer 8

B-hemolytic streptococci (Group A S. pyogenes & Group B S. agalactiae)

Question 9

What microbe is a cause of impetigo in kids?

Answer 9

GAS (Group A S. pyogenes)

Question 10

What microbes are common inhabitants of the mouth but rarely spread to skin?

Answer 10

a-hemolytic streptocci (S. viridans & S. penumoniae)

Question 11

Gram - microbial inhabitants of the skin

Answer 11

Enterobacter
Klebsiella
E. coli

Question 12

Microbes that are often found under nails

Answer 12

Fungi

Question 13

How can keratinocytes act as innate immune players (besides being a physical defense)

Answer 13

1. TLRs
2. Cytokines/Chemokines (TNF-a, IL-1, IL-6)
3. Antimicrobial Peptides (AMPs) (b-defensins, LL37))

Question 14

immunologic defense mechanism of keratinocytes; example are b-defensins (LL37); will accumulate on the microbe, and if a high enough concentration is reached, will punch holes in membrane and form irregular structure, so makes resistance difficult

Answer 14

Antimicrobial Peptides (AMPs)

Question 15

How does Staph. epidermidis, a normal skin flora, help “educate” CD8+ T-cells?

Answer 15

1. Dendritic cells “sample” S. epidermidis angitens and present to CD8+ T cells
2. Keratinocytes respond by enhancing barrier function and limiting pathogen invasion

Question 16

Atopic Dermatitis is usually caused by an infection of

Answer 16

S. aureus

Question 17

Why is Atopic Dermatitis more common in developed countries?

Answer 17

Improved sanitation–> dec. skin microflora–> less T-cell “education”–> exaggerated inflammation to infections

Question 18

Common bacteria that infect skin

Answer 18

Staph. aureus

Strep. pyogenes

Question 19

Common fungi that infect skin

Answer 19

dermatophytes

candida

Question 20

Common viruses that infect skin

Answer 20

Childhood viruses
VZV
Molluscum contagiosum
Human Papillomavirus

Question 21

Toxins produced by Staph. aureus and Strep. pyogenes can cause toxic shock via…

Answer 21

Superantigens (trigger MASSIVE polyclonal expansion of T-cells and a cytokine storm)

Question 22

Massive polyclonal expansion of T-cells and cytokine storm is also known as

Answer 22

Mitogen

Question 23

Which cutaneous bacteria can cause toxic shock via a superantigen response

Answer 23

Staph. aureus

Strep. pyogenes

Question 24

What are other cutaneous virulence factors of S. aureus?

Answer 24

1. Exfoliative toxins
   - Exotoxins A-D
   - Cause Staphylococcal Scalded Skin Syndrome
2. Resistance to AMP

Question 25

What toxins are non-mitogenic, cleave desmoglein causing intraepidermal splitting

Answer 25

Exotoxins A-D

Question 26

Bacteria implicated for Scalded Skin Syndrome (serious peeling of the skin) via cleaving desmoglein proteins

Answer 26

Staph. aureus

Question 27

dermal bacterial infection; obligate intracellular Gram - bacteria; TICK BORNE; causes Rocky Mountain Spotted Fever

Answer 27

Rickettsia rickettsii

Question 28

dermal bacterial infection; Gram - bacteria; frequent colonizer of the nasopharynx; can cause disseminated infection including MENINGITIS

Answer 28

Neisseria meningitidis

Question 29

dermal bacterial infection; sexually transmitted spirochete; rash characteristic of SECONDARY SYPHILIS

Answer 29

T. pallidum

Question 30

class of microbes that can infect the skin; keratinophilic (love keratin); most common is T. rubrum; can cause superficial infections such as "ringworm" or "tinea"

Answer 30

dermatophytes

Question 31

Common genera of dermatophytes

Answer 31

Trichophyton Microsporum Epidermophyton

Question 32

MOST common dermatophyte

Answer 32

T. rubrum

Question 33

What fungal virulence factors are associated with hyphal elements?

Answer 33

Keratinases Proteases Lipases

Question 34

What can predispose you to a Candida albicans skin infection

Answer 34

``` Antibiotics (disrupts normal flora) Steroids Diabetes Obesity Immunocompromised pts ```

Question 35

Viral pediatric infections: Enveloped RNA viruses

Answer 35

Measles Rubella *Included in MMR vaccine

Question 36

Viral pediatric infections: Non-Enveloped DNA virus

Answer 36

Parvo B19 (cause red cheeks)

Question 37

Viral pediatric infection: Enveloped DNA virus

Answer 37

HHV 6/7 (roseola)

Question 38

Cutaneous virus that is associated with warts; non-enveloped DNA virus

Answer 38

HPV (Human Papillomaviruses)

Question 39

Cutaneous virus that is associated with Molluscum contagiosum (umbilicated papules); enveloped DNA virus

Answer 39

Poxvirus

Question 40

Cutaneous virus that is associated with Chickenpox (primary infection) and Shingles (reactivation); herpes virus

Answer 40

VZV (herpesvirus)

Question 41

VZV affect what type of cells?

Answer 41

Neurons

Question 42

small, ds, circular DNA virus that is ubiquitous and infect external cutaneous skin and mucosal membranes

Answer 42

HPV (Human papillomaviruses)

Question 43

Why does VZV, a cutaneous viral infection, cause a dermatome distribution

Answer 43

Reactivates along dermatome of sensory nerves of dorsal root ganglia

Question 44

Two types of shingles vaccines

Answer 44

1. Zostavax | 2. Shingarix (reduce chances of zoster by 90%; preferred by CDC)

Question 45

What shingles vaccine has live, attenuated virus and is contraindicated for immunocompromised people or pregnant women?

Answer 45

Zostavax

Question 46

What shingles vaccine has recombinant viral antigen + adjuvent; no contraindication

Answer 46

Shingarix