Infective Endocarditis Flashcards
Epidemiology
uncommon
adults
slightly more in males
usually on the valves more so than other areas of endocardium
Characteristics
causes “vegetations”
vegetations
friable masses of blood clot and infecting organisms
friable
the ability of a solid substance to be reduced to smaller pieces with little effort.
pathogenesis
- valvular endothelial injury
- platelet and fibrin deposition
- microbial seeding
- microbial multiplication
prognosis
100% fatal if undiagnosed and untreated
20% fatal if diagnosed and treated appropriately (IV antibiotics and/or surgery)
3 classification systems
- clinical course
- host substrate
- specific infecting organism
classification via clinical course
acute bacterial endocarditis (ABE) vs.
subacute bacterial endocarditis (SBE)
ABE
usually fulminant and due to highly virulent organisms (i.e. S. aureus)
SBE
insidious onset over weeks and due to less virulent organisms (viridans streptococci)
classification via host substrate
native valve endocarditis (NVE) versus
Prosthetic valve endocarditis (PVE) versus
edocarditis in IVDU
PVE
commonly due to coag negative S. epidermis, which is rare in NVE
Endocarditis in IVDU
commonly acute and commonly on tricuspid valve
classification via specific infecting organism
i.e. pseudomonas aeruginosa endocarditis
Anatomic sites of IE
Left-sided valves….75%
Right-sided valves…15%
Both…5%
Other…..5%
Mitral valve alone....35%-------| Aortic valve alone...20%-------|-->75% Mitral and aortic...20%---------| Tricuspid...14%------| Pulmonic....1%------|-->15%
What percentage of pts w/ IE have predisposing heart disease?
70%
What are some predisposing heart diseases?
MVP congenital disease prosthetic valve degenerative disease rheumatic disease previous endocarditis
portals of entry for organisms causing IE
central venous catheterization endoscopy shaving dental procedures gingivitis chewing brushing teeth surgery bladder catheterization IVDU etc.
correlation b/w ability of bug to cause IE and its ability to…
adhere to blood clot
dextran
facilitates adherence of some streptococci to blood cot
(cell wall component)
esp. streptococcus mutans… a viridans that causes dental caries by same MOA
Most common etiological agents of IE in tertiary care hospitals
- Staphylococci in 42%
—-S. aureus in 32%
—-CoagNS in 10% - Streptococci 40%
—-Viridans group (oral flora) 18%
—-enterococci 11%
—-S. bovis (assoc. w/ colon cancer) in 6%
—-others 5%
(In RURAL settings, viridans=more common cause than S. aureus!) - HACEK group bacteria 4%
- other gram-negative aerobes 3%
- fungi (esp. Candida) 2%
NEGATVE BLOOD CULTURES or multiple causative organisms…9%
HACEK
fastidious slow-growing oral flora)
gross pathology
–large (up to 3cm), friable vegetations
(some combo of tan, gray, red, or brown)
–range of # of vegetation (1 to many)
–vegetations usually located on line of valve closure (the atrial side of AV valves, or ventricular side of semilunar valves)
the larger the vegetation…
the more likely it is to be infected
IE consequences
destructive of tissue may cause perforation of valve adjacent abscess fibrotic scarring calcification
microscopic pathology of the vegetations
fibrin
platelets
masses of organisms
sometimes necrois and neutrophils
later, lymphocytes, macrophages, fibroblasts may infiltrate and fibrosis may occur
Common symptoms
**fever
chills
weakness
dyspnea
Less common symptoms
cough sweats anorexia weight loss malaise skin lesions nausea/vomiting stroke headache myalgia/arrthralgia edema chest pain abdominal pain delirium/coma back pain hemptysis
Common physical signs
fever
heart murmur
splenomegaly
petechiae
uncommon physical signs
Osler nodes subungual splinter hemorrhages changing heart murmur Janeway lesions new heart murmur Roth spots
Osler nodes
pea-sized tender finger/toe nodules
Janeway lesions
small palm/sole hemorrhages
Roth spots
white dots w/ surrounding hemorrhage in retina
Uncommon signs vs common signs
the uncommon signs are more specific
Common lab findings
elevated ESR
circulating immune complexes
anemia
proteinuria
Less common lab findings
rheumatoid factor hematuria leukocytosis hypergammaglobulinemia elevated creatinine leukopenia thrombocytopenia
Rheumatoid factor
anti-IgG antibodies
characteristic of endocarditis
continuous low-grade bacteremia
Blood cultures
Some types need special cultures for fastidious organisms…hod cultures longer
**critical for specific diagnosis
may be negative if already received antibiotics
What can show vegetations in 60% of cases?
transthoracic echocardiography
what has greater than 90% sensitivity?
transesophageal echocardiography
does the absence of vegetations on echocardiogram exclude diagnosis of endocarditis?
No!
Duke Criteria for infective endocarditis
requires 2 major, OR
1 major and 3 minor, OR
5 minor criteria fulfilled for a diagnosis
Complications
HF septic emboli --kidneys --heart --spleen --brain
More uncommon complications
Myocardial abscess
GN
“mycotic aneurysm”
pericarditis
If suspect IE…
don’t wait for echo…
get the blood cultures, put “suspect endocarditis” on requisition, and
start antibiotic therapy!
