Staphylococcus

Question 1

What are physical characteristics of Staph?

Answer 1

Gram Positive cocci, nonmotile
Clusters
Facultative Anaerobes

Question 2

Where is staph normally located in our normal flora?

Answer 2

Upper Respiratory Tract. 25% of people are carriers

Question 3

What is a key difference between S. Aureus and S. Saprophyticus/Epidermidis?

Answer 3

S. Aureus is coagulase positive and the others are not.

Question 4

Difference between Staph and Strep?

Answer 4

Staph is Catalase Positive
Strep is Catalase Negative
-Can use peroxide to see if bubbles

Question 5

What is the unique morphology of S. Aureus?

Answer 5

Protein A on its outer surface bound to peptioglycan, which bind the Fc regions of IgG molecules preventing opsonization/phagocytosis.

Question 6

What are the toxins that S. Aureus can produce?

Answer 6

B-Hemolysin
Leukotoxins
Enterotoxins
Exfoliative Toxins

Question 7

What can enterotoxins cause and where are they from?

Answer 7

Enterotoxins are super toxins usually from contaminated food and cause intoxication to the person n/v/d between 2-6 hours after ingestion that resolve shortly there after.

Question 8

What is super antigen and how does it work?

Answer 8

Superantigens are enterotoxins that can cause intoxication and toxic shock syndrome. The toxin can nonspecifically bind the MHC receptor and TCR causing mass activation and cytokine release.

Question 9

How do exfoliative toxins work and what can they cause?

Answer 9

Exfoliative toxins are proteases that cleave the intracellular attachment of epithelial cells. ETA/ETB forms.
SCALDED SKIN SYNDROME

Question 10

How is Staph typically transferred?

Answer 10

Transferred via direct contact on the hands. Can reside on the skin since oxygen tolerant.

Question 11

What are common infections of Staph?

Answer 11

Folliculitis, Abscesses, Impetigo (mixed staph/strep), scalded skin syndrome, and Pneumonia (immunocompromised)

Question 12

Where is the primary site of infection of Staph?

Answer 12

Skin infections. Primary barrier of protection is intact skin.

Question 13

How can Staph Aureus become resistant to penicillin/methicillin? How is it treated?

Answer 13

Changes in the PBP (Penicillin Binding Proteins)

Treated with Vancomycin.

Question 14

What is a characteristic of S. Epidermidis?

Answer 14

Typically gotten while in the hospital localized at surgical sites and can bind to plastics. Multiple Drug Resistance.

Question 15

How is S. Saphrophyticus unique?

Answer 15

Binds/infects the urinary tract and does not have any known virulence factors.