19 Microbial Diseases of the Skin and Wounds

Question 1

Describe three reasons why the skin is not well suited for the growth of most microbes.

Answer 1

Multilayered, dry, salty, and acidic.

Question 2

Describe the normal microbiota (microbiome/flora) of the human skin.

Answer 2

diphtheroid, staphylococci, and fungu

Question 3

Name two reasons why Cutibacterium acnes is well suited to growing in hair follicles.

Answer 3

uses sebum as metabolite and produces propionic acid which decreases the pH so it can grow well.

Question 4

What enzyme do most pathogenic Staphylococci produce?

Answer 4

coagulase

Question 5

Name one species of Staphylococcus that is typically referred to as a CNS (coagulase negative Staphylococcus).

Answer 5

S. epidermidis

Question 6

pimple

Answer 6

clogged pore

Question 7

sty

Answer 7

infection of eye lash follicle

Question 8

furuncle

Answer 8

localized pocket of pus surrounded by inflamed tissue

Question 9

carbuncle

Answer 9

fusion of 2 or more furuncles, rounded and deeper

Question 10

Describe some physical and growth characteristics of Staphylococcus.

Answer 10

facultative anaerobic Gram-positive coccus, grow in clusters, pairs and occasionally in short chains.

Question 11

vesicles and bullae

Answer 11

thin walled inflammations that are close to the surface. Bullae are larger

Question 12

pustules

Answer 12

deep pocket of pus

Question 13

staphylococcal scalded skin syndrome
a. the causative agent, bacterial group
b. method of transmission
c. what causes the exfoliation associated with this disease?

Answer 13

a. staph aureus
b. nosocomial, person to person or fomites
c. exfoliative toxin produced by some strains which is released when the bacteria is lysogenized by a phage

Question 14

What genus and species is synonymous with group A (beta-hemolytic) streptococci?

Answer 14

Streptococcus pyogenes

Question 15

Describe the virulence factors that contribute to the pathogenicity of streptococci.

Answer 15

M protein- antiphagotic
capsule made of hyaluronic acid
erythogenic toxins that cause rash and fever
streptolysin S lyses neutrophils and RBC

Question 16

pyoderma and erysipelas:
a. the causative agent(s), bacterial group
b. signs and symptoms
c. mechanism of transmission

Answer 16

a. staph aureus and sometimes strep pyrogenes
b. pustules and pus-filled vesicles that break open and crust over w/o healing
c. person to person in breaks in the skin (insect bites or cold sores)

Question 17

necrotizing fasciitis:
a. causative agent, bacterial group
b. alternate name
c. signs and symptoms

Answer 17

a. strep pyrogenes
b. flesh eating bacteria
c. intense pain and blackening of tissues, open wounds

Question 18

cellulitis:
a. causative agent, bacterial group
b. mechanism of transmission
c. signs and symptoms

Answer 18

a. staph aureus and strep pyrogenes
b. not transmitted, deep tissue infection
c. red inflamed skin on lower limbs

Question 19

cat scratch disease:
a. causative agent
b. transmission
c. signs and symptoms

Answer 19

a. Bartonella henselae
b. bite, lick, or scratch from infected cat
c. pustule at site of entry, swollen lymph nodes, headache and fever

Question 20

Describe some infections caused by Pseudomonas and key characteristics.

Answer 20

otitis externa and opportunistic infections
green discharge

Question 21

Rocky Mountain Spotted Fever (RMSF):
a. the causative agent and bacterial group
b. method of transmission (common name for the vector)
c. signs and symptoms

Answer 21

a. rickettsia ricketsii
b. tick bite
c. headache, joint/muscle pain, fever, rash begins on hands and feet

Question 22

anthrax:
a. causative agent
b. various forms of the disease

Answer 22

a. bacillus anthracis
b. inhalation, cutaneous, and intestinal

Question 23

gas gangrene:
a. the causative agent, bacterial group
b. treatment

Answer 23

a. Clostridium perfringens
b. debridement, amputation, hyperbaric chamber

Question 24

Compare and contrast HHV-1 (HSV-1) and HHV-2 (HSV-2).

Answer 24

HHV1: cold sores, transmission by saliva or direct contact, usually above waist, latent in trigeminal ganglion
HHV2: genital, sometimes oral, sexually transmitted, below the waist, latent in sacral ganglion

Question 25

warts:
a. causative agent
b. transmission and pathogenesis
c. treatments

Answer 25

a. HPV
b. transmitted through fomites, direct contact, or autoinoculation. Multiples in skin cells and sheds in dead skin cells.

Question 26

smallpox:
a. transmission
b. signs and symptoms

Answer 26

a. droplet or direct contact
b. fever, headache, and skin lesions that leave severe scars

Question 27

chicken pox:
a. transmission
b. conditions that increase the risk of Reye’s syndrome

Answer 27

a. direct contact, inhalation of aerosols from vesicular fluid of skin lesions of acute varicella or zoster, and possibly through infected respiratory secretions that also may be aerosolized.
b. aspirin ingestion increases risk

Question 28

Explain how varicella-herpes zoster causes shingles.

Answer 28

virus lays dormant in dorsal root ganglia and travels along peripheral nerve to face or torso resulting in severe pain

Question 29

List some other “childhood” rashes caused by viruses that we immunize against.

Answer 29

measles and rubella

Question 30

Distinguish between the various tineas (cutaneous mycoses) caused by dermatophytes.

Answer 30

tinea pedis (athlete’s foot)
tinea corporis (whole body)
tinea capitis (ring worm)
tinea cruris (jock itch)
tinea unguium (nail bed)

Question 31

leishmaniasis:
a. causative agent
b. transmission
c. signs and symptoms of the various forms of the disease

Answer 31

a. leishmania genus
b. sandfly bite
c. visceral disease: reoccurring fever, enlarged spleen and liver, weight loss
cutaneous disease: disfiguring sores

Question 32

scabies:
a. causative agent
b. transmission
c. signs and symptoms
d. a common secondary infection

Answer 32

a. sarcoptes scabiei mite
b. shared fomites or sexual contact
c. raised pimple like rash that blisters
d. impetigo