Infective Endocarditis,
A disease resulting from infection primarily of the valvular
endocardium and occasionally the mural endocardium
Acute endocarditis: Aggressive course,
usually caused by more virulent organisms, such as Staphylococcus aureus, group B streptococcus,may not have underlying valve lesion
Subacute endocarditis: Indolent course, usually caused by
alpha-hemolytic streptococci, enterococci (usually in
setting of underlying structural valve disease)
Endocarditis in
intravenous drug abusers: Commonly involves the tricuspid valve. Staphylococcus
aureus is the most common infecting organism.
Early prosthetic valve endocarditis: Occurs
within 60 days of valve implantation. Staphylococci, gram-negative bacilli and
Candida are common infecting organisms.
Late prosthetic valve endocarditis: Occurs 60
days or longer after valve implantation. Staphylococcus epidermidis,
alpha-hemolytic streptococci and enterococci are
common infecting organisms.
System(s) affected: Cardiovascular, Skin/Exocrine, Pulmonary,
Endocrine/Metabolic, Renal/Urologic, Hemic/Lymphatic/Immunologic
Incidence/Prevalence in
Predominant age: All ages
Predominant sex: Male > Female (slightly)
SIGNS AND SYMPTOMS
Fever, may be high, low or absent. May be only
symptom in prosthetic valve endocarditis.
Night sweats, chilly sensation
Malaise, myalgia, joint pain
Back pain, may be severe
Anorexia, weight loss
Stiff neck
Delirium, headache
Paralysis, hemiparesis, aphasia
Numbness, muscle weakness
Cold extremity with pain
Bloody urine, may be gross or microscopic
Bloody sputum, from septic pulmonary emboli
Petechiae
Conjunctival
hemorrhage
Hemorrhagic or necrotic pustule
Pain of finger tip, or toe tip (subjective symptom of Osler node)
Chest pain, shortness of breath, cough
Pallor
Roth spot
Osler node
Janeway lesion
Heart murmur, may be absent
Neck vein distention
Gallops
Rales
Cardiac arrhythmia
Pericardial rub
Pleural friction rub
Splenomegaly
CAUSES
Staphylococcus aureus is a causative organism
in all types of endocarditis, especially acute endocarditis and endocarditis
seen in IV drug abusers
Acute endocarditis
Staphylococcus aureus
Streptococcus groups A, B, C, G
Haemophilus influenzae
Haemophilus parainfluenzae
Streptococcus pneumoniae
Staphylococcus lugdunensis
Enterococcus
species
Neisseria gonorrhoeae
Subacute endocarditis
Alpha-hemolytic streptococci (viridans
streptococci)
Streptococcus bovis
Enterococcus
species (E. faecalis, E. faecium,
E. durans)
Haemophilus aphrophilus and H. paraphrophilus
Actinobacillus actinomycetemcomitans
Cardiobacterium hominis
Eikenella corrodens
Kingella kingae
Staphylococcus aureus
Endocarditis in
intravenous drug-abusers
Staphylococcus aureus
Pseudomonas aeruginosa
Burkholderia cepacia
Other gram-negative bacilli
Enterococcus
species
Candida species
Early prosthetic valve endocarditis
Staphylococcus aureus
Staphylococcus epidermidis
Gram-negative bacilli
Candida species
Aspergillus species
Late prosthetic valve endocarditis
Alpha-hemolytic streptococci (viridans
streptococci)
Enterococcus
species
Staphylococcus epidermidis
Candida species
Aspergillus
species
Culture-negative endocarditis
5–10%
Patients on antibiotics
Bartonella quintana (homeless people)
Bartonella henselae (cat owners)
Brucella
Fungi
Coxiella burnetii (Q fever)
Chlamydia trachomatis
Chlamydia psittaci
RISK FACTORS
Conditions predisposed to development of endocarditis
Prosthetic cardiac valves, including bioprosthetic
and homograft valves
Previous bacterial endocarditis, even in the
absence of heart disease
Most congenital cardiac malformations
Rheumatic and other acquired valvular
dysfunction, even after valvular surgery
Hypertrophic cardiomyopathy
Mitral valve
prolapse with valvular
regurgitation
Indwelling intravascular devices
Dental or surgical procedures that may cause transient bacteremia leading to endocarditis
in susceptible hosts
Dental procedures known to produce gingival irritation, including
professional cleaning
Tonsillectomy and/or adenoidectomy
Surgical operations that involve intestinal or respiratory mucosa
Bronchoscopy with a
rigid bronchoscope
Sclerotherapy for
esophageal varices
Esophageal dilatation
Gallbladder surgery
Cystoscopy
Urethral dilatation
Urethral catheterization if urinary tract infection is present
Urinary tract surgery if urinary tract infection is present
Prostatic
surgery
Incision and drainage of infected tissue
Vaginal hysterectomy
Vaginal delivery in the presence of infection
LABORATORY
Positive blood cultures taken at different times
2-dimensional echocardiography, not always positive for vegetations (transesophageal echocardiography has high sensitivity)
Leukocytosis in
acute endocarditis
Anemia in subacute endocarditis
Elevated erythrocyte sedimentation rate
Decreased C3, C4, CH50 in subacute endocarditis
Hematuria,
microscopic or macroscopic
Rheumatoid factor in subacute endocarditis
Serologies for
Chlamydia, Q fever (Coxiella) and Bartonella
may be useful in “culture-negative” endocarditis
Drugs that may alter lab results: Antibiotics may make blood cultures
falsely negative
Disorders that may alter lab results:
Endocarditis caused
by fungi, Chlamydia trachomatis, Chlamydia psittaci, Coxiella burnetii, Bartonella species may
be associated with negative blood cultures
Prolonged incubation of blood cultures is needed in endocarditis
caused by fastidious organisms, e.g., HACEK organisms (Haemophilus
species, Actinobacillus actinomycetemcomitans,
Cardiobacterium hominis, Eikenella corrodens, Kingella species), Brucella
species
PATHOLOGICAL FINDINGS
Vegetations on the affected endocardium are
composed of platelets, fibrin and colonies of micro-organisms. Destruction of valvular endocardium, perforation
of valve leaflets, rupture of chordae tendineae, abscesses of myocardium, rupture of sinus of Valsalva, pericarditis may occur.
Emboli and/or infarction may be found in different body organs.
Abscesses and micro-abscesses may be found in different organs. Kidneys may
show embolic and/or immune-complex glomerulonephritis.
IMAGING
Pulmonary ventilation perfusion scan may be useful in right-sided endocarditis
Computerized axial tomographic scan may be
useful in locating abscesses
DIAGNOSTIC PROCEDURES
Transesophageal
echocardiography is useful, especially in prosthetic or bioprosthetic
valve endocarditis and S. aureus
endocarditis associated with intravascular catheter
Cardiac catheterization may be indicated to ascertain the degree of valvular damage
Aortic root injection may be useful when aortic root abscess or rupture
of sinus of Valsalva is suspected
Duke criteria for diagnosis of infective endocarditis
2 major criteria, or
1 major and 3 minor criteria, or
5 minor criteria
Major criteria
Positive blood culture
- Typical microorganism for infective endocarditis
from 2 separate blood cultures: Viridans
streptococci, † Streptococcus bovis, HACEK † group,
or community acquired Staphylococcus aureus or enterococci, in the absence of a primary focus, or
- Persistently positive blood culture. Defined as recovery of a
microorganism consistent with infective endocarditis
from: blood cultures drawn more than 12 hours apart, or all of 3 or a majority
of 4 or more separate blood cultures, with first and last drawn at least 1 hour
apart
Evidence of endocardial involvement
Positive echocardiogram: (a) oscillating intracardiac
mass, on valve or supporting structures, or in the path of regurgitant
jets, or on implanted material, in the absence of an alternative anatomic
explanation, or (b) abscess, or (c) new partial dehiscence of prosthetic valve
New valvular regurgitation (increase or
change in pre-existing murmur not sufficient)
Minor criteria
Predisposition: predisposing heart condition or intravenous drug use
Fever ≥ 38.0°C (100.4°F)
Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhage, Janeway
lesions
Immunologic phenomena: glomerulonephritis, Osler’s nodes, Roth spots, rheumatoid factor
Microbiologic evidence: positive blood culture, but not meeting major
criterion as noted previously † or serologic evidence of active infection with
organism consistent with infective endocarditis
Echocardiogram: consistent with infective endocarditis
but not meeting major criterion as previous noted
† Including nutritional variant strains
†† HACEK = Haemophilus spp,
Actinobacillus actinomycetemcomitans,
Cardiobacterium hominis, Eikenella spp, Kingella kingae
††† Excluding single positive cultures for coagulase-negative
staphylococci and organisms that do not cause endocarditis
TREATMENT
APPROPRIATE HEALTH CARE
Initial hospitalized care
Intensive care may be needed in critically ill patients
Outpatient home intravenous antibiotic therapy may be utilized in
selected patients who are stable and reliable
GENERAL MEASURES
Treatment for congestive heart failure if it occurs
Oxygen treatment may be indicated
Hemodialysis may be
used in patients who develop renal failure
SURGICAL MEASURES
Cardiac surgery to replace infected valve may be performed before
antibiotic treatment course is completed when (any one):
There is evidence of congestive heart failure due to valve
incompetence,
Multiple major systemic emboli have occurred,
The infection is caused by resistant organisms, e.g., fungus,
Pseudomonas aeruginosa,
There is dehiscence of infected prosthetic valve,
There is relapse of prosthetic valve endocarditis,
There is persistent bacteremia despite
antibiotic treatment
ACTIVITY
Bedrest is indicated
initially
Ambulation when clinically improved
DIET No special diet
PATIENT EDUCATION
Instruct patient regarding importance of dental hygiene
Emphasize to patient that it is important to take antibiotic
prophylaxis when undergoing certain dental/surgical procedures
Give the patient an AHA wallet card listing antibiotic regimens for
prophylaxis. Obtain the AHA wallet card, 78–1005 (CP), from local chapters of
American Heart Association.
MEDICATIONS DRUG(S) OF CHOICE
Endocarditis due to
penicillin-susceptible viridans streptococci and
Streptococcus bovis: Aqueous crystalline penicillin G
10–20 million U/24 h IV in 4–6 equally divided doses, plus gentamicin
[see Other Notes] for 2 weeks (6 weeks for prosthetic valve endocarditis).
In patients with native valve endocarditis: Those
older than 65 years of age, those with impairment of the eighth nerve or of
renal function, or those with central nervous system involvement, use aqueous
crystalline penicillin G only, in the same dosage alone for 4 weeks.
Endocarditis due to
enterococci: Aqueous crystalline penicillin G 20–40 million U/24 h in 6 equally divided doses, plus gentamicin (see Other Notes) for 4–6 weeks (6 weeks for
prosthetic valve endocarditis). Test the enterococcal strain in vitro for high-level resistance to gentamicin and streptomycin (minimal inhibitory
concentration [MIC] > 2000 µg/mL). Use
streptomycin, 1 gm IM every 24 hours, instead of gentamicin
if there is high-level resistance to gentamicin and
not to streptomycin.
Endocarditis of
native valve due to staphylococcus: Oxacillin or nafcillin 2 g IV every 4 h for 6 weeks. For the first 3–5
days, gentamicin (see Other Notes) may be added.
Prosthetic valve endocarditis due to
staphylococci: Vancomycin 15 mg/kg (usual dose 1 g)
IV infused over 1 h every 12 h, plus rifampin 300 mg po every 8 h, both for 6 weeks, plus gentamicin
(see Other Notes) for the first 2 weeks
Endocarditis due to
HACEK organisms (Haemophilus species, Actinobacillus actinomycetemcomitans,
Cardiobacterium hominis, Eikenella corrodens, Kingella kingae) - ceftriaxone 2 gm IM or IV every 24 h for 4 weeks
Contraindications: For patients who are allergic to penicillin, use
alternative drugs
Precautions:
In patients with renal impairment, dosage adjustment should be made for
penicillin G, gentamicin, cefazolin,
vancomycin
Rapid infusion of vancomycin (less than one
hour) may cause “red-neck syndrome”, an intense redness or rash over the upper
half of the body. This is due to histamine release and not an allergic reaction.
It will disappear when the rate of infusion is reduced.
Significant possible interactions:
The combination of vancomycin and gentamicin may cause increased incidence of renal toxicity
Rifampin may
increase the requirement for coumarin oral anticoagulant
and oral hypoglycemic agents
ALTERNATIVE DRUGS
For patients who are allergic to penicillin
Endocarditis due to
penicillin-susceptible viridans streptococci and
Streptococcus bovis: ceftriaxone
2 g IM or IV once daily for 4 weeks or ceftriaxone 2
g IV plus gentamicin 3 mg/kg once daily for 2 weeks
(not to be used in patients with immediate type hypersensitivity to
penicillin), or vancomycin 15 mg/kg (usual dose 1 g)
IV infused over 1 h every 12 h for 4 weeks (6 weeks for prosthetic valve endocarditis)
Endocarditis due to
enterococci: Desensitization to penicillin should be
considered. Vancomycin 15 mg/kg (usual dose 1 g) IV
infused over 1 h every 12 h, plus gentamicin (see
Other Notes) for 4–6 weeks (6 weeks for prosthetic valve endocarditis).
Endocarditis of
native valve due to staphylococcus: Cefazolin 2 gm IV
every 8 h (not to be used in patients with immediate-type hypersensitivity to
penicillin), or vancomycin 15 mg/kg (usual dose 1 g)
IV infused over 1 h every 12 h, for 6 weeks
FOLLOWUP
PATIENT MONITORING
Gentamicin blood
levels should be performed if used for more than 5 days, and in patients with
renal dysfunction. Peak gentamicin level should be
around 3 µg/mL and trough less than 1 µg/mL.
Vancomycin blood
levels should be performed in patients with renal dysfunction. Desired peak
level is 30–45 mcg/mL and trough less
than 10 mcg/mL.
Twice weekly BUN and serum creatinine should
be performed while the patient is receiving gentamicin
Consider audiometry baseline and follow-up
during long-term aminoglycoside therapy
PREVENTION/AVOIDANCE
Dental caries should be treated while the patient is being treated for endocarditis
Patients should maintain good oral hygiene
Antibiotic prophylaxis should be given to the patient who is undergoing
dental or surgical procedures that may cause transient bacteremia
Standard antibiotic regimen for dental/oral/upper respiratory tract
procedures: (may be used in patients with prosthetic valves)
Amoxicillin 2 g orally 1 h before procedure
For patients who are allergic to penicillin: clindamycin
600 mg orally 1 h before a procedure
Alternate antibiotic regimens for dental/oral/upper respiratory tract
procedures
For patients unable to take oral medications: Ampicillin
2.0 g IV (or IM) 30 minutes before procedure
For patients who are allergic to penicillin: Clindamycin
600 mg IV 30 minutes before a procedure
Standard antibiotic regimen for genitourinary/gastrointestinal
procedures
Ampicillin 2.0 g
IV (or IM) plus gentamicin 1.5 mg/kg IV (or IM) (not
to exceed 120 mg) 30 minutes before procedure
For patients who are allergic to penicillin: vancomycin
1.0 g IV infused over one hour plus gentamicin 1.5
mg/kg IV (or IM) (not to exceed 120 mg); complete infusion 30 minutes before
procedure
Alternate oral regimen for moderate-risk patients undergoing
genitourinary/gastrointestinal procedures
Amoxicillin 2.0 g orally one hour before procedure or ampicillin 2 g IV (or IM) 30 minutes before procedure
For patients who are allergic to penicillin: vancomycin
1.0 g IV infused over 1 hour; complete infusion 30 minutes before procedure
POSSIBLE COMPLICATIONS
Congestive heart failure
Ruptured valve cusp
Sinus of Valsalva aneurysm
Aortic root abscesses
Myocardial abscesses
Myocardial infarction
Pericarditis
Cardiac arrhythmia
Meningitis
Cerebral emboli
Brain abscesses
Ruptured mycotic aneurysm
Septic pulmonary infarcts
Splenic
infarcts
Arterial emboli and infarcts
Arthritis
Myositis
Glomerulonephritis
Acute renal failure
Mesenteric infarct
EXPECTED COURSE/PROGNOSIS
In staphylococcal endocarditis, fever and
positive blood cultures may persist up to 10 days after appropriate treatment
started
In streptococcal endocarditis, there should
be clinical response within 48 hours of antibiotic treatment and blood cultures
should be negative soon after antibiotic treatment is started
Prognosis depends largely on the possible complications
MISCELLANEOUS
ASSOCIATED CONDITIONS
Most patients who have tricuspid valve endocarditis
are intravenous drug abusers or have indwelling IV lines
Geriatric: Prognosis is worse in elderly people
PREGNANCY
Gentamicin should
be used with caution; avoid use if possible
SYNONYMS
Bacterial endocarditis
Infectious endocarditis
Subacute
bacterial endocarditis
Subacute
infective endocarditis
Acute bacterial endocarditis
Acute infective endocarditis
OTHER NOTES
Gentamicin
dosing: 3 mg/kg/day in divided doses every 8–12 hours, depending on renal
function and results of peak/trough measures.