Flashcards in Infective Endocarditis (SBE, ABE) Deck (20)
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.
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
IE Risk Factors
Age>60 years->50% cases
Male sex-3:2 to 9:1
Injection drug use
IE Comorbid Conditions
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
IE, Clinical Manifestations
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)
IE Symptoms and Signs
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
Coag negative staph-11%
Non HACEK gram negative-2%
HACEK-2%, includes Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae.
Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae.
Increase in incidence from 2000 to 2011 from 11 to 15 cases/100,000 population
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
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.
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.
IE Duke Criteria
micro organism recovered from tissue (embolus, abscess, culture)
Histologic proof of organism
2 major or
1 major and 3 minor
Possible IE Duke criteria
1 major and 1 minor
or 3 minor
Reject the IE diagnosis if...
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
Duke Major Criteria- blood cultures
Positive blood culture
Typical micro organism for IE from two separate blood cultures;
Strep gallolyticus (bovis)
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
Other duke major
New valvular regurgitation
Fever (100.4 F, 38 C)
Positive blood cultures not meeting above major criteria
Serologic evidence of infection
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.