Bacterial Skin Infections

Question 1

Folliculitis:

Answer 1

Pyogenic infection in the hair follicles.

Question 2

Furuncles:

Answer 2

Boils, extension of folliculitis.

Question 3

Carbuncles:

Answer 3

Infection extends to the deeper subcutaneous tissue with a single inflammatory mass.

Question 4

Spreading infection confined to the epidermis:

Answer 4

Impetigo

Question 5

Spreading infection involving the dermal lymphatics:

Answer 5

Erysipelas

Question 6

Cellulitis:

Answer 6

When the major factor is the subcutaneous fat layer.

Question 7

Macules:

Answer 7

Flat, non-palpable lesions.

Question 8

Papules:

Answer 8

Palpable lesions.

Question 9

Vesicles:

Answer 9

Palpable, fluid filled lesions.

Question 10

Pustules:

Answer 10

Palpable and contain pus.

Question 11

Bulla:

Answer 11

Collection of serous fluid and have small numbers of inflammatory cells.

Question 12

Common cause of impetigo (2):

Answer 12

• Strep pyogenes

- Staph aureus

Question 13

Common cause of erysipelas:

Answer 13

Strep pyogenes

Question 14

Common cause of folliculitis, furuncles and carbuncles:

Answer 14

Staph aureus

Question 15

Common cause of necrotizing fasciitis:

Answer 15

Anaerobes and microaerophiles, usually mixed infections.

Question 16

Common cause of myonecrosis gangrene:

Answer 16

Clostridium perfringens

Question 17

Skin manifestation of Salmonella:

Answer 17

“Rose spots” containing bacteria.

Question 18

Skin manifestation of pseudomonas:

Answer 18

Ecthyma gangrenosum

Question 19

Skin manifestation of strep pyogenes:

Answer 19

Erythematous rash (toxin)

Question 20

Skin manifestation of Staph aureus:

Answer 20

Rash and desquamation (toxin)

Question 21

Virulence factors of S. aureus (5):

Answer 21

• Staph toxins
• Exfoliative toxins
• Enterotoxins
• Toxic shock syndrome toxins
• Enzymes

Question 22

Impetigo (4):

Answer 22

• Contagious superficial infection
• Primarily seen in young children
• Purulent with crusting
• Caused by strep pyogenes +/- staph aureus

Question 23

Pustular impetigo (4):

Answer 23

• Intraepidermal vesicles filled with exudate.
• Crusted lesions
• Caused by strep pyogenes or staph aureus
• Seen in exposed areas of the body during warm, moist weather

Question 24

Bullous impetigo (5):

Answer 24

• Localized staph scalded skin syndrome
• Caused by staph aureus that produces exfoliative toxin A
• Newborns and young children
• Culture positive
• No Nikolsky’s sign

Question 25

Erysipelas (4):

Answer 25

• Tender, superficial erythematous and edematous lesions
• Spreads primarily in upper dermis and superficial lymphatics
• Mainly young and elders
• Caused by strep pyogenes

Question 26

Majority of cellulites is caused by:

Answer 26

Strep pyogenes and staph aureus

Question 27

Necrotizing fasciitis:

Answer 27

Deep seated infection of the subcutaneous tissue leading to destruction of fascia and fat, but may spare skin.

Question 28

Type I necrotizing fasciitis:

Answer 28

Mixed infection caused by aerobic and anaerobic bacteria.

Occurs most commonly after surgical procedures, DM, and PVD.

Question 29

Type II necrotizing fasciitis:

Answer 29

Caused by strep pyogenes or staph aureus.

Question 30

Necrotizing fasciitis caused by v. vulnificus:

Answer 30

Rapidly progressive wound infections after exposure to contaminated sea water.

Question 31

Myonecrosis:

Answer 31

Necrotizing infection of muscle.

Question 32

Staph scalded skin syndrome (4):

Answer 32

Ritter’s disease

• Perioral erythema covers entire body w/in 2 days
• Positive Nikolsky’s sign
• Large blister with clear fluid, no organism, no leukocytes
• Exfoliative toxin destroys the intracellular connections in the skin

Question 33

Mycobacterium leprae (2):

Answer 33

• An obligately aerobic rod with Gram positive-like cell wall
• Grow best in skin histocytes, endothelial cells and schwann cells

Question 34

Treatment for lepromatous leprosy:

Answer 34

Triple therapy with dapsone, ribiospfampin and clofazimine x 2 years.

Question 35

Treatment for tuberculoid leprosy:

Answer 35

Dapsone and rifampin for 6 months.

Question 36

Bacillus anthracis (3):

Answer 36

• Gram positive, spore forming
• Capsule
• Exotoxin:
  
  • Edema factor
  • Lethal factor
  • Protective antigen

Question 37

Lethal factor:

Answer 37

A protease that induces macrophage to produce high levels of cytokines that trigger the shock.

Question 38

Inhalation anthrax (3):

Answer 38

• Inhalation of aerosolized spores
• Mediastinal widening
• Replication occurs within the lung with local exotoxin release.