PBL Stuff

Question 1

most common organisms that cause endocarditis: Native Valve Endocarditis (Community Acquired)

Answer 1

Streptococci* 40%
Staphylococcus aureus 28%
Enterococci** 9%
Culture-negative 9%
Coagulase-negative staphylococci 5%
* - includes viridans streptococci, Streptococcus gallolyticus, and other non-group A streptococci.
** - primarily Enterococcus faecalis.

Question 2

most common organisms that cause endocarditis: Native Valve Endocarditis (Nosocomial)

Answer 2

Staphylococcus aureus*** 52%
Enterococci** 16%
Streptococci* 13%
Coagulase-negative staphylococci 11%
Polymicrobial, miscellaneous, culture-negative 6%
* - includes viridans streptococci, Streptococcus gallolyticus, and other non-group A streptococci.
** - primarily Enterococcus faecalis.
*** - methacillin resistance is common.

Question 3

most common organisms that cause endocarditis: Endocarditis in Injection Drug Users (total)

Answer 3

Staphylococcus aureus 57%
Streptococci* 12%
Enterococci** 9%
Gram-negative bacilli 7%
Polymicrobial / miscellaneous 7%
* - includes viridans streptococci, Streptococcus gallolyticus, and other non-group A streptococci.
** - primarily Enterococcus faecalis.

Question 4

S. mutans

Answer 4

Gram +
Cocci
Catalase -
Alpha-hemolytic
bacitracin resistant

Question 5

S. pyogenes

Answer 5

Gram + 
Cocci
Catalase -
Beta-hemolytic
Bacitracin sensitive

Question 6

Gamma hemolysis -

Answer 6

Doesn’t damage red blood cells at all - so it can grow on plate and there is no color change

Question 7

Alpha hemolysis -

Answer 7

Viridans, partial degradation of red blood cells, leads to color change/oxidation and turns surrounding area green

Question 8

Beta hemolysis -

Answer 8

Group A strep (streptococus pyogenes), will completely destroy red blood cells

Question 9

Strep Viridans: virulence factors

Answer 9

Needs some kind of damage for colonization event. Makes Dextran for Glycocalyx formation and surface adhesion proteins for colonization. M protein keeps bacteria from being phagocytosed and the complement-activation cascade.

Question 10

Staph Aureus Virulence Factors -

Answer 10

o   Biofilm Formation
o   Protein A (binds Fc portion of IgG)
o   Coagulase – activates fibrinogen
o   Capsule
o   Adhesins
o   Pathogenicity Islands (Methicillin Resistance)

Question 11

ECHO is

Answer 11

the superior for imaging structures that are thin and highly mobile owing to its greater temporal resolution and the absence of partial volume effects.

Question 12

Transesophageal echocardiography (TEE)

Answer 12

TEE is used when there is an inability to get clear imaging through standard ECHO.
TEE provides more detailed information on the size, shape, and movement of heart muscle, the condition of the aorta, how the heart valves are working, and the quality of blood flow through the heart and arteries.
Done with a swallowed probe; more expensive, higher risk

Question 13

Cardiovascular magnetic resonance (CMR)

Answer 13

Has the potential to visualize all parts of the valve (leaflets, chordae tendineae, and papillary muscles) throughout the entire cardiac cycle. Congenitally abnormal valve leaflets (bicuspid), aberrant papillary muscles or aberrant chordal attachments (parachute mitral valve), leaflet thickening, presence and extent of calcification, leaflet redundancy and prolapse, and commissural fusion are all anatomic descriptions that have been reported by CMR.

Although 2D echocardiography remains the primary approach for visualization of valve anatomy, CMR is a reasonable alternative if ultrasound windows are poor.

Question 14

tPA:

Answer 14

converts plaminogen to plasmin which degrades fibrin clots
Streptokinase: biosynthetic form of tPA

Benefits: increase functional independence without affecting mortality at 3-6 months if given within 3 hours
Risks: intracranial hemorrhage within the first 7 days after administration
Contraindications: Suspected/Confirmed endocarditis, intracranial hemorrhage on CT, clinical presentation suggests subarachnoid hemorrhage, neurological surgery, head trauma or stroke in past three months, uncontrolled hypertension

Question 15

Ceftriaxone:

Answer 15

Binds to penicillin binding proteins and inhibits peptidoglycan synthesis. Broad spectrum for Gram positive and negative organisms.

Question 16

Vancomycin:

Answer 16

Forms H-bonds with D-ala-D-alanine and prevents the incorporation of NAM/NAG-peptide subunits into peptidoglycan matrix. Broad spectrum for Gram positive and negative organisms.

Question 17

Penicillin G:

Answer 17

Beta- lactam ring binds to DD-transpeptidase inhibiting cross-linking for remodeling of peptidoglycan. Inhibits transpeptidase. Narrow spectrum of Gram positive, aerobic organisms.

Question 18

Describe physical exam findings associated with emboli

Answer 18

Splinter hemorrhages under the fingernails 
Stroke 
Petechiae
Roth spots  
Pulmonary Emboli → MI

Question 19

penetrance means

Answer 19

The percentage of individuals with a given genotype who exhibit the phenotype associated with that genotype.

Question 20

differentiate PTSD from generalized anxiety

Answer 20

Prior trauma → differentiates PTSD from generalized anxiety and/or cardiac symptoms
“Traumatic situations outside the usual human experience”

Question 21

KNOW that you need to draw blood for blood cultures BEFORE giving prophylactic antibiotics

Answer 21

know it!