What is the #1 circulatory system infection?
Infective Endocarditis - infection of endothelial sites in the heart
What is the two highest causes of Infective Endocarditis?
- Bacteria
- Yeast
What are the ways of increasing risk of infective endocarditis?
Bacterial Source + Susceptible Host
- Bacterial Source*s:
- Breach of barriers taht separate us from normal flora (gut, mouth)
- Infection elsewhere in body that seeds the blood (indwelling vascular devices, abscessess, pyelonephritis)
- Organisms introduced during surgery or through IV drug use
- *Causes of Susceptible Host_ _Risk:**
- Preexisting valve damage (congenital defects, scar tissue)
- Native, healthy valves attached by aggressive microbe
- Prosthetic replacement valves
What populations are most at risk for Infective Endocarditis?
- IV drug users
- Prosthetic valve replacement (immediately after surgery; after some time their risk is same as native valve)
- Native valve infection
What are risk factors for infective endocarditis?
IV drug use
Mitral valve prolapse
Congenital or Degenerative valve disease
Poor dentition and oral hygiene
Genitourinary manipulations or bowel surgery
Prosthetic heart valves
HIV (reflects association with IV drug use AND invasive therapeutics)
Long-term hemodialysis
Rheumatic heart disease (#1 predisposing risk factor in developing world)
What are characteristics of Group A Strep?
Gram + Cocci
Beta-hemolytic
Catalase negative
Bacitracin sensitive
Causes impetigo, Strep Throat, and rheumatic fever
What is rheumatic heart disease?
Caused by untreated infection of Group A Strep
M-Protein (helical anti-phagocytic protein) on surface of Group A Strep is anti-phagocytic due to molecular mimicry
Engenders anti-cardiac antibody responsible for deposits and thickening of leaflets and RHD
What is the pathology of infective endocarditis?
Primary lesion = vegetation
- A collection of patelets, fibrin, microorganisms and inflammatory cells
- Generally occurs on valves, may also occur at site of septal defect, on chordae tendinae, or mural endocardium
What are the three types of bacteremia?
Transient: bacteria introduced into blood stream and readily cleard w/o evoking a detectable inflammatory response
Intermittent: spread of infection from some extra-vascular site; results in fever, inflammatory response
Continuous: seeded into blood streem from site of infection within circulatory system
What is Acute Endocarditis?
Fulminant Disease
(occuring suddenly, rapidly, and with great severity or intensity)
- Fever, chills
- Pronounced heart murmur
- Symptoms of stroke
- Clinical signs of embolic infection
- Frequently healthy valves are affected
–Often seen in IV drug users–
What is sub-acute endocarditis?
Gradual onset
- Fatigue, malaise
- fever
- night sweats, weight loss
- cough
- symptoms of congestive heart failure
- usually assoc. with preexisting valve disease
What are clinical signs of endocarditis?
- Splinter hemorrhages under fingernails or toenails (result of infection disseminating to extremeties)
- Conjunctival petechiae
- Osler’s nodes: tender, subcutaneous nodules, oftten in pulp of digits or thenar eminence
- Janeway’s Lesions: nontender erythematous, hemorrhagic, or pustular lesions, often on palms or soles of feet
Why does IE predominantly affect the LEFT side of the heart?
- Relatively higher pressures on L side produce more turbulent flow across mitral and aortic valves; predisposing them to endothelial damage
- Relatively higher O2 content of L side circulation more supportive of bacterial growth
- More common congenital and acquired lesions of L heart valves
What increases chances of right sided endocarditis?
Associated with IV Drug use
(Staph Aureus, usually)
Occurs in tricuspid valve defects as well
What are complications of IE
Intracardiac Damage:
Permanent valvular damage
Perivalvular damage
Congestive Heart failure
Extracardiac Damage:
Seeding of other organs with infective agent
Splenic, renal abscesses
Meningeal or brain abscesses
Vascular Damage:
“Septic Emboli”
Stroke-like symptoms
“Mycotic” aneurysm
Immune Complex Disease (Type III):
Glomerulonephritis
What are major bacterial causes of endocarditis?
Native Valve Endocarditis: **Oral flora or GI flora (subacute) Staph aureus (acute)**
Prosthetic Valve endocarditis:
Early = Staph epidermidis, Staph aureus
Late - endogenous oral or GI flora
Intravenous drug abuse endocarditis:
Staph aureus
Candida Albicans
What are the three hemolytic patterns and how do they appear in a gel?
Alpha = green
Beta = clear/yellow (complete hemolysis)
Gamma = none
What are characteristics and examples of oral streptococal species?
- Mostly alpha hemolytic
- Termed “viridans” group strep (green)
- Cause dental caries, biofilms on the teeth (plaque)
- Not highly pathogenic
- Major species:
Strep sanguis
Strep mitis - Strep mutans
What oral flora (associated with peridontitis) are also common in IE?
Gram Negative Bacilli
HACEK:
Haemophilus parainfluenze
Aggregatibacter acetomyecetecomitans and aphophilus
Cardiobacterium hominis
Eikenella corrodens
Kingella kingae
What are characteristics of Staph epidermidis?
- Ubiquitous on skin, surfaces, hospital settings
- Not as virulent as S. aureus
- Coagulase negative
- White colonies, non-hemolytic
- Often multiple drug resistance
- Common in nosocomial post-surgical infections (esp. prosthetics)
What are characteristics of Staph aureus?
- Gram + cocci in clusters
- Beta hemolytic
- Catalase +
- Coagulase +
- Common on skin (often carried in nose)
- Causative agent of boils, folliculitis, impetigo, severe soft tissue and bone infections, TSS, as well as bacterial endocarditis
What are Endocarditis bacteria associated with GI cancers, urogenital infections?
- Enterococcus
- Strep bovis
- E. coli
- Yeast
- Other gram - bacilli
- often gamma hemolytic
What are characteristics of Enterococcus?
- Group D bacteria
- Tolerant of bile salts (hence gut niche; “entero”)
- Gamma Hemolytic
- Resistant to 6.5% NaCl
- Hydrolize bile exculin (BE+)
- Lead Species:
E. faecium
E. faecalis
What is required to make a diagnosis of infectous endocarditis?
- Lab data (esp. repeat + blood cultures)
- Positive echocardiogram
- Risk factors
- Fever
- Vascular and immunologic signs (Splinter hemorrhages, petechiae, Oslar’s nodes, etc)
