Staphylococcus Species

Question 1

What common characteristics to all Staphylococcus species share?

Answer 1

1. **Gram positive cocci **in pairs, clusters, chains
2. Non-motile
3. Facultative anaerobes
4. Catalase positive

Question 2

If you have a slide of gram positive cocci in pairs on a microscope, how can you tell if it is staph or strep?

Answer 2

Staph are catalase positive and will bubble when H₂O₂ is applied. Strep are catalase negative and won’t bubble.

Question 3

How is the *Staphylococcus aureus *metabolically different than the other Staph species?

Answer 3

It is coagulase positive

Question 4

What role does Protein A have in the virulence of Staphylococcus aureus?

Answer 4

It has a covalent bond to PDG
It disrupts opsonization and lysis by impairing IgG binding.

Question 5

What role do hemolysins have in the virulence of Staph. aureus**?

Answer 5

They are beta-hemolytic and damage the RBC membrane. This promotes tissue damage.

Question 6

What role does leukotoxin have in the virulence of Staph. aureus?

Answer 6

It attacks PMN leukocytes and macrophages.

Question 7

What three “assault weaponry” toxins are secreted by Staph. aureus?

What effect does each toxin create?

Answer 7

Enterotoxin - diarrhea & emesis in 2-6 hours from preformed toxin ingestion

TSST - 1 - responsible for staph based toxic shock

Exfoliative toxin - 2 forms ETA/ETB. Stimulates lysis of epidermis and Scalded Skin Syndrome

Question 8

What is the primary site of *Staph. aureus *infections?

Answer 8

Skin

Question 9

What are some hallmarks of Staph Toxic Shock Syndrome?

Answer 9

High fever
Watery diarrhea
Erythematous rash
Hypotension
Desquamation of palms and soles

Question 10

What is the treatment for *Staphylococcus aureus *infection?

Answer 10

Penicillin for non-MRSA
Vancomycin for MRSA

Question 11

What would a *Staphylococcus *specific gram stain look like?

Answer 11

Gram-positive cocci in clusters

Question 12

What would a Staph. aureus specific culture look like?

Answer 12

Beta-hemolytic with a golden yellow pigment

Question 13

What organism is a Gram positive cocci that is Beta-hemolytic, catalase-positive, coagulase-positive?

Answer 13

Staphylococcus aureus

Question 14

1. How is Staphylococcus epidermidis typically acquired?
2. How is it treated?

Answer 14

1. Nosocomial infections at surgical sites.
2. Individual sensitivity must be run. Resistance is a BIG PROBLEM!

Question 15

What is unique about Staph saprophyticus in culture on blood agar?

Answer 15

It is gamma-hemolytic

Question 16

Which Staph species is a common contaminant of blood cultures?

Answer 16

Staph epidermidis (similar to a surgical site)

Question 17

Which *Staph *species is a common cause of UTI in sexually active women?

Answer 17

Staphylococcus saprophyticus