HES Lecture 1

Question 1

Cause of Bullous impetigo

Answer 1

S. aureus infection causing cloudy bacterial filled erosions due to exfoliate toxin.

Question 2

Cause of Ecthyma?

Answer 2

Punched out ulcerative lesions result of emitigo that has bee neglected resulting in scarring and ulceration.

Question 3

Cause and Identification of Erysipelas?

Answer 3

S. pyogenes
Involved red skin has a distinct border of infection.
Usually preceded by respiratory or skin GAS infection.

Question 4

Cause and identification of cellulitis?

Answer 4

Hard to determine as there are many causes. Most likely S. pyogenes, can be from Pasterurella if bitten by cat or dog, with salt water can be vibrio vulnificans.

Differs from Erysipelas as border is not clearly determinable.

Question 5

Cause of acute paronychia vs chronic paronychia?

Answer 5

Acture: S. pyogenes

Chronic >6 weeks C. albicans.

Question 6

What are the two none coagulase staphylococcus?

Answer 6

S. epidermidis and S. saprophyticus.

Question 7

Slime layer/biofilm that faciliates adherence to foreign bodies and is antiphagocytic

Answer 7

S. Aureus Capsule virulence factor

Question 8

Provides Endotoxin-like activity

Answer 8

Peptidoglycan

Question 9

Provides adhesion for S. Aureus

Answer 9

Teichoic acid

Question 10

Inhibits antibody mediated clearance by binding to IgG Fc domain when secreted by S. aureus?

Answer 10

Protein A

Question 11

What virulence factor does S. aureus produce that causes Staphylococcus Scalded Skin Syndrome?

Answer 11

Exfoliative toxins which are serine proteases that split intraepidermal junctions.

Question 12

Which are superantigens, exotoxins or cytotoxins?

Answer 12

Cytotoxins are toxic to all cells - Alpha is a pore forming toxin.

Enterotoxins are superantigens associated with food poisoning.

Question 13

How does Staphylococcyl Scalded Skin Syndrome typically begin and what mediates it?

Answer 13

Begins with an infection of the nairs with S. aureus and is mediated by the toxin exfolin.
Bacteria will not be found in the shedding of blisters!

Question 14

What are the three stages of staphylococcyl scalded skin syndrome?

Answer 14

Initial stage: Redened skin
Exfoliative stage: Skin forms blisters that peel off with minimal pressure (Nikolsy’s sign) skin under peeling appears sun burnt.
Desquamation stage: After 4-5 days of the exfoliative stage, by day 7-10 the skin sloughs off and appears normal.

Question 15

What specifically does Exfoliative toxin split?

Answer 15

Acts as a serine protease that splits desmoglein-1 found in the stratum granulosum epidermis.

Question 16

If cutaneous S. aureus is not removed by opening the wound and cleaning out any foreign objects, what else can be done to cure it?

Answer 16

Use of antibiotics:
Naficillin 
Oxacillin
Cefazolin
"NOC - semisynthetic penicillins"

Question 17

What is MRSA teated with ?

Answer 17

Vancomycin

Question 18

What is the most common cause of septic arthrits in sexually active adults?

How about those who have recieved joint injections?

Answer 18

Gonorrhea is most common is sexually active adults

S. aureus tends to invade mechanically abnormal joints.