MHD: Cardiac infections

Question 1

List the heart valves in order of most likely to least likely to be affected by endocarditis

Answer 1

Mitral, aortic, tricuspid, pulmonary

Question 2

What are the two types of infective endocarditis?

Answer 2

Subacute: associated with viridans Strep
Acute: associated with Staph aureus

Question 3

What organisms are most likely to infect a native heart valve?

Answer 3

Streptococci (60-80%)
Staphylococci (20-35%)
HACEK

Question 4

What organisms are most likely to infect a prosthetic heart valve

Answer 4

Staph aureus

Staph epidermidis

Question 5

What organisms are most likely to infect a prosthetic heart valve >2 months after surgery?

Answer 5

Viridans strep
Staph epidermidis
Staph aureus

Question 6

What organisms are most likely to cause infective endocarditis in IV drug users?

Answer 6

Staph aureus
G- bacilli (Pseudomonas)
Viridans strep
Candida

Question 7

What is the most common cause of IE in community hospitals?

Answer 7

Staphylococci

Question 8

What are the HACEK organisms?

Answer 8

Haemophilus
Actinobacillus
Cardiobacterium
Eikenella
Kingella

Question 9

What are the characteristic lesions associated with IE?

Answer 9

Splinter hemorrhages
Janeway lesions
Osler nodes
Roth Spots

Question 10

What is the mechanism for lesion formation in IE?

Answer 10

Vegetations dislodge from valve surface and embolize to small vessels

Question 11

What are the most common physical exam findings in infectious endocarditis?

Answer 11

Fever (90%)
Murmur (85%)
Peripheral lesions are far less frequent (

Question 12

What is the timing difference between acute and subacute endocarditis?

Answer 12

Acute: rapid onset, 2-5 days
Subacute: 2-5 weeks

Question 13

What is nonbacterial thrombotic endocarditis?

Answer 13

Tissue damage of a valve leads to formation of a thrombus. This thrombus can serve as a site for microorganism attachment

Question 14

What property do organisms that are associated with IE have that non-associated organisms do not?

Answer 14

IE causing organisms adhere more avidly to normal heart valves due to adhesins: dextran, Fim A attach to damaged epithelia

Question 15

What are the major lab studies for confirming diagnosis of infective endocarditis?

Answer 15

Blood cultures: growth from more than 1 sample

Transesophageal echocardiography: valve damage visible

Question 16

What are the minor criteria for diagnosis of infective endocarditis?

Answer 16

1) Predisposing heart disease or IV drug use
2) High body temperature
3) Evidence of vascular phenomena
4) Immunological phenomena
5) Microbiologic evidence

Question 17

General, how is infective endocarditis treated?

Answer 17

Combination antimicrobial therapy for several weeks

Question 18

Describe the synergism in antibiotic treatment of IE

Answer 18

Cell wall synthesis inhibitors enhance the entry of aminoglycosides into the bacteria