Brown Checkpoint 1

Question 1

What are some of the common symptoms patients present with in IE cases?

Answer 1

a. Heart murmur, new/worsened regurgitant murmur, peripheral manifestations (osler’s nodes, subungual hemorrhages, Janeway lesions, Roth’s spots)
i. Fever, chills sweats

Question 2

2. What are some of the pre-existing health issues and behaviors that predispose patients to IE?

Answer 2

a. Prosthetic heart valve or repair with prosthetic material, hx. Of endocarditis, heart transplant with abnormal heart valve function, congenital heart defects (valve/ prosthetic issues)
b. Asplenic pt’s

Question 3

3. Most cases of infective endocarditis occur on the left side valves of the heart (mitral, aortic). However, right side infective endocarditis is more common in which type of patient?

Answer 3

a. IV drug users

Question 4

4. What are some of the most common causes of IE?

Answer 4

a. S. aureus most common cause of acute IE (31%), S. Viridans most common cause of subacute IE (17%), enterococci (11%), coag-neg staph (11%), strep bovis (7%), non-HACEK gram-neg bac (2%), fungi (2%), HACEK (2%)

Question 5

5. How is the Duke Criteria used to confirm IE?

Answer 5

a. IE has substantial range in onset and can be difficult to dx. Helps guide dx.
b. 2 major, 1 major 3 minor, or 5 minor
c. major
i. Pos blood cultures, evidence of endocardial involvement
d. minor
i. Predisposition, fever, vascular phenomena, immunologic phenomena, micro evidence, echo findings

Question 6

6. Why does the Duke criteria require multiple blood draws at least an hour apart?

Answer 6

a. False positives due to skin contamination and transient bacteremia very common

Question 7

7. What are some of the common reasons a patient may have IE, but be negative during blood draws for bacteria?

Answer 7

a. Pt. on antibiotics, bacteremia is transient and missed by single blood draw, bacteria may not be consistently thrown off the valve, Coxiella burnetii and Bartonella spp. Are fastidious bacteria

Question 8

8. How is S. aureus distinguished from S. epidermidis in routine lab test/cultures (see table)?

Answer 8

a. Staph aureus is coag pos.

Question 9

9. Which two agars are commonly used to culture staphylococci? Be able to describe the appearance of S. aureus and epidermidis when grown on these agars.

Answer 9

a. Sheeps blood agar, S. aureus is B-hemolytic and s. epidermidis is gamma-hemolytic
b. Mannitol salt agar, s. aureus will ferment mannitol into lactic acid and cause yellow hue

Question 10

10. What are some of the common diseases caused by S. aureus and S. epidermidis?

Answer 10

a. S. aureus
i. Pneumonia, meningitis, osteomyelitis, septic arthritis, bacteremia/sepsis, UTI, skin infections, nec fasc
b. S. epidermidis
i. Nosocomial infections of prosthetics

Question 11

11. What are the main virulence factors associated with S. aureus and S. epidermidis?

Answer 11

a. S. aureus
i. Protein A, coagulase, hemolysin, leukocydin (PVL), polysaccharide capsule
b. S. epidermidis
i. Polysaccharide capsule (biofilm), broad antibiotic resistance

Question 12

12. What disease(s) are associated with B. henselae? B. quintana?

Answer 12

a. B. henselae: cat-scratch fever (typically contracted from bite or scratch, more rarely exposure of open wound to a cat
b. B. Quintana: trench fever- transmission through human body louse

Question 13

13. In patients with Bartonella IE, why are blood cultures rarely usefully for the initial diagnosis?

Answer 13

a. Bacteria are fastidious and take long time to grow

Question 14

14. Besides culture, what are some of the ways one can confirm a Bartonella infection?

Answer 14

a. If tissue samples available PCR can be used, silver staining works better than gram staining