3.1.3 Staphylococci

Question 1

List general characteristics of bacteria in the genus Staphylococcus (gram, shape, arrangement, catalase status)

Answer 1

Gram +, cocci, clusters, catalase +

Question 2

Staphylococcus is catalase ____ and oxidase ____

Answer 2

Positive, negative

Question 3

What are some of the dz’s caused by staphylococcus?

Answer 3

1 cause of infective endocarditis, nosocomial bloodstream infections, and orthopedic ones

Septic shock mortality rate is high

Question 4

What is the most virulent species of the Staphylococcus genus?

Answer 4

Staph. aureus

Question 5

What do MSSA and MRSA stand for?

Answer 5

Methicillin-susceptible Staph. aureus

Methicillin-resistant Staph. aureus

Question 6

Most MRSA infections in hospitals are typically acquired where?

Answer 6

CA-MRSA

Question 7

What causes foodborne intoxication with staphylococcus?

Answer 7

Ingestion of heat-stable enterotoxin (transmitted by food handlers)

Question 8

Describe the onset of food intoxication seen with staphylococcus

Answer 8

Rapid onset (within 1-6 h)

Question 9

What are some of the clinical syndromes seen with Staph aureus?

Answer 9

LOL

Question 10

What are the major virulence factors of S. aureus?

Answer 10

4 cytolysins

leukocidins

modulins

Enterotoxins

Adherence factors (Protein A, fibronectin-binding proteins, collagen-binding proteins)

Other secreted enzymes

Question 11

What is the main type of infections is most common with S. aureus?

Answer 11

Skin/soft tissue infection (95%)

-cellulitis, impetigo, abcess/furuncle

Question 12

What this be?

Answer 12

Abscess/furuncle

Question 13

What is this? Which toxin is responsible?

Answer 13

Scalded Skin Syndrome (SSS) - Ritter’s syndrome

Exfoliative toxins ETA and ETB

Question 14

What age group is most at risk for SSS?

Answer 14

Children under 5

Question 15

This skin desquamation is a result of which toxin? What is the name of this syndrome?

Answer 15

Toxic Shock Syndrome (TSS) - shock w/n 48 hrs

Superantigen

Question 16

What is the mechanism of TSST-1 toxin?

Answer 16

Binds T cell receptor and MHCII of APC => constituitively active

Leads to massive release of cytokines -> hypotension, shock, and death

Question 17

Infection of bone or bone marrow

Answer 17

Osteomyelitis

Question 18

What cardiac abnormality is associated with S. aureus?

Answer 18

Question 19

What are some of the Respiratory tract infections associated with S. aureus?

Answer 19

Pneumonia, empyema, cystic fibrosis

Question 20

What are the two topical rx options for S. aureus?

Answer 20

Bacitracin (MSSA > MRSA)

Mupirocin (MSSA and MRSA)

Question 21

What are the different rx options for MSSA and MRSA?

Answer 21

Question 22

What morphilogical change is associated with VISA? VRSA?

Answer 22

VISA (Vancomycin-intermediate S. aureus) - thickened cell wall

VRSA (Vancomycin-resistant S. aureus) - acquired resistance plasmid from Enterococci

Question 23

What is the coagulase status of S. epidermidis?

Answer 23

Negative

Question 24

What are some of the opportunistic infections of S. epidermidis?

Answer 24

Primary implant, catheter and prosthetic joints, bacteremia (biofilm)

Question 25

What type of infections is S. saprophyticus famous for?

Answer 25

UTIs in sexually active young women

Question 26

Answer 26

Question 27

What is produced by S. epidermidis that inhibits growth of other gram positiives?

Answer 27

Bacteriocins