Infective Endocarditis (SBE, ABE)

Question 1

IE diagnosis

Answer 1

Positive blood cultures are the cornerstone of the diagnosis.

Three sets of blood cultures detect 96-98% of bactremia. Since the bactremia of IE is continuous, there is no reason to time the culture with fever or chills. Three sets of cultures from different sites should be obtained PRIOR to the initiation of antibiotics.

Question 2

IE cultures

Answer 2

The diagnostic yield of more then 3 blood cultures is small, and can be confusing (contaminants, etc.)
Most clinically significant cultures are positive in 48 hours, an exception is slow growing bacteria like the HACEK group

Question 3

IE Risk Factors

Answer 3

Age>60 years->50% cases
Male sex-3:2 to 9:1
Injection drug use
Poor dentition
Comorbid Conditions

Question 4

IE Comorbid Conditions

Answer 4

1. Structural heart disease, Rheumatic
2. Valvular heart disease
3. Congenital heart disease
4. Prosthetic heart valves
5. History of IE
6. Presence of intravascular device
7. Chronic HD
8. HIV

Question 5

IE, Clinical Manifestations

Answer 5

May present acutely, as rapidly progressive or more slowly as a sub acute or chronic disease.
Acute presentation may be due to the organism of infection (Staph aureus), it’s virulence, method of transmission (IV drug abuse) or host suspectibility (immunocomprised)

Question 6

IE Symptoms and Signs

Answer 6

Fever-90%
General symptoms of infection, malaise, chills, anorexia, joint pain, headache, etc
Cardiac murmur 85%, regurgitant if primary (that is due to the infection), but my develop on stenotic valves

Question 7

Microbiology

Answer 7

Staphylococcus aureus-31%
Strep viridans-17%
Enterococci-11%
Coag negative staph-11%
Strep bovis-7%
Other strep-5%
Non HACEK gram negative-2%

Fungi-2%
HACEK-2%, includes Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae.

Question 8

HACEK

Answer 8

Haemophilus aphrophilus

Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae.

Question 9

IE Epidemiology

Answer 9

Increase in incidence from 2000 to 2011 from 11 to 15 cases/100,000 population

Question 10

IE presents

Answer 10

Usually presents acutely not sub acutely (as before antibiotic age)
Careful clinical history focused on indwelling prosthetic devices such as; IV catheters, orthopedic hardware, cardiac devices.
IV drug use/abuse is one of the most important factors

Question 11

IE PE

Answer 11

PE should focus on new regurgitant murmurs and CHF
Look for stigmata of endocarditis to include, subungual hemorrhage, Roth spots, Janeway lesions, Osler nodes. Remember most of these are signs of sub acute, not acute disease and they will be absent.

Question 12

IE diagnosis

Answer 12

Modified Duke criteria are used.
The diagnosis is usually straight forward if the pathogen is obtained on blood culture, it is likely to cause endocarditis and there is evidence of endocardial involvement.

Question 13

IE Duke Criteria

Answer 13

Definite IE
 Pathologic criteria
  micro organism recovered from tissue (embolus, abscess, culture)
  Histologic proof of organism
 Clinical criteria
  2 major or
  1 major and 3 minor
  5 minor

Question 14

Possible IE Duke criteria

Answer 14

1 major and 1 minor

or 3 minor

Question 15

Reject the IE diagnosis if…

Answer 15

firm alternative diagnosis or
resolution of manifestations with 4 days of antibiotics or

No pathologic evidence of IE at surgery or autopsy after only 4 days of Rx
Does not meet Duke criteria

Question 16

Duke Major Criteria- blood cultures

Answer 16

Positive blood culture
 Typical micro organism for IE from two separate blood cultures;
   Viridans Strep
   Strep gallolyticus (bovis)
   HACEK group
   Staph aureus
   Community acquired enterocci or

Persistently positive blood cultures;
blood cultures drawn more then 12 hours apart, or
¾ positive cultures
Single positive culture for Coxiella burnetii or antiphase I IgG antibody titer >1:800

Evidence of endocardial involvement
Very important

Question 17

Other duke major

Answer 17

Positive echocardiogram

New valvular regurgitation

Question 18

Duke minor

Answer 18

Predisposition
Fever (100.4 F, 38 C)
Vascular findings
Immunologic findings
Positive blood cultures not meeting above major criteria
Serologic evidence of infection

Question 19

Blood cultures

Answer 19

Obtain blood cultures prior to iniation of antibiotics, if feasible (“do no harm”)
At least 3 sets of cultures
Separate sites, not catheter
Typical organisms are Staph Aureus, viridian strep, strep bovis, enterococci and HACEK group.

Question 20

Echocardiogram

Answer 20

Should be obtained in all patients, a TTE first, TEE if indicated