Infective Endocarditis
Infective endocarditis includes acute and subacute bacterial
endocarditis, as well as nonbacterial endocarditis caused by
viruses, fungi, and other microbiologic agents.
ETIOLOGY.
Viridans-type streptococci (α-hemolytic streptococci) and
Staphylococcus aureus are the leading causative agents for
endocarditis in pediatric patients. Many patients with culturenegative endocarditis have Q fever (Coxiella burnetii) or
Bartonella species. Staphylococcal endocarditis is more common
in patients with no underlying heart disease; viridans group
streptococcal infection is more common after dental procedures;
group D enterococci are seen more often after lower bowel or
genitourinary manipulation; Pseudomonas aeruginosa or Serratia
marcescens is seen more frequently in intravenous drug users; and
fungal organisms are encountered after open heart surgery.
Coagulase-negative staphylococci are common in the presence of
an indwelling central venous catheter.
EPIDEMIOLOGY.
Infective endocarditis is often a complication of congenital or
rheumatic heart disease but can also occur in children without any
abnormal valves or cardiac malformations. In developed countries,
congenital heart disease is the overwhelming predisposing factor.
Endocarditis is rare in infancy; in this age group, it usually follows
open heart surgery or is associated with a central venous line.
Patients with congenital heart lesions in which blood is ejected at
high velocity through a hole or stenotic orifice are most susceptible
to endocarditis. Vegetations usually form at the site of the
endocardial or intimal erosion that results from the turbulent flow.
Children with ventricular septal defects (VSDs), left-sided valvular
disease such as aortic stenosis, tetralogy of Fallot, and systemicpulmonary arterial communications (patent ductus arteriosus or
Blalock-Taussig shunts) are at highest risk. In older patients,
congenital bicuspid aortic valves and mitral valve prolapse with
regurgitation pose additional risks for endocarditis. Surgical
correction of congenital heart disease may reduce but does not
eliminate the risk of endocarditis, with the exception of repair of a
simple atrial septal defect or patent ductus arteriosus. Children who
have undergone valve replacement or valved conduit repair are
also at high risk
Manifestations of Infective Endocarditis
HISTORY
Prior congenital or rheumatic heart disease
Preceding dental, urinary tract, or intestinal procedure
Intravenous drug use
Central venous catheter
Prosthetic heart valve
SYMPTOMS
Fever
Chills
Chest and abdominal pain
Arthralgia, myalgia
Dyspnea
Malaise
Night sweats
Weight loss
CNS manifestations (stroke, seizures, headache)
SIGNS
Elevated temperature
Tachycardia
Embolic phenomena (Roth spots, petechiae, splinter nail bed hemorrhages, Osler
nodes, CNS or ocular lesions)
Janeway lesions
New or changing murmur
Splenomegaly
Arthritis
Heart failure
Arrhythmias
Metastatic infection (arthritis, meningitis, mycotic arterial aneurysm, pericarditis,
abscesses, septic pulmonary emboli)
Clubbing
LABORATORY
Positive blood culture
Elevated erythrocyte sedimentation rate; may be low with heart or renal failure
Elevated C-reactive protein
Anemia
Leukocytosis
Immune complexes
Hypergammaglobulinemia
Hypocomplementemia
Cryoglobulinemia
Rheumatoid factor
Hematuria
Renal failure: azotemia, high creatinine (glomerulonephritis)
Chest radiograph: bilateral infiltrates, nodules, pleural effusions
Echocardiographic evidence of valve vegetations, prosthetic valve dysfunction or
leak, myocardial abscess, new-onset valve insufficiency
DIAGNOSIS.
The critical information for appropriate treatment of infective
endocarditis is obtained from blood cultures. All other laboratory
data are secondary in importance. Blood specimens for culture
should be obtained as promptly as possible, even if the child feels
well and has no other physical findings.
The Duke criteria help in the diagnosis of endocarditis. Major
criteria include (1) positive blood cultures (two separate cultures
for a usual pathogen, two or more for less typical pathogens) and
(2) evidence of endocarditis on echocardiography (intracardiac
mass on a valve or other site, regurgitant flow near a prosthesis,
abscess, partial dehiscence of prosthetic valves, or new valve
regurgitant flow). Minor criteria include predisposing conditions,
fever, embolic-vascular signs, immune complex phenomena
(glomerulonephritis, arthritis, rheumatoid factor, Osler nodes,
Roth spots), a single positive blood culture or serologic evidence
of infection, and echocardiographic signs not meeting the major
criteria. Two major criteria, one major and three minor, or five
minor criteria suggest definite endocarditis. A modification of the
Duke criteria may increase sensitivity while maintaining
specificity. The following minor criteria are added to those already
listed: the presence of newly diagnosed clubbing, splenomegaly,
splinter hemorrhages, and petechiae; a high erythrocyte
sedimentation rate; a high C-reactive protein level; and the
presence of central nonfeeding lines, peripheral lines, and
microscopic hematuria.
PREVENTION.
Recommendations of the American Heart Association for Prophylaxis Against
Bacterial Endocarditis
DENTAL AND ORAL PROCEDURES OR SURGERY OF THE UPPER
RESPIRATORY
TRACT OR ESOPHAGUS
GASTROINTESTINAL AND
GENITOURINARY TRACT SURGERY
AND INSTRUMENTATION
For most
patients
High-risk
patients
Oral amoxicillin
Adults, 2.0 g,
IM or IV ampicillin
Adults, 2.0 g, children, 50
DENTAL AND ORAL PROCEDURES OR SURGERY OF THE UPPER
RESPIRATORY
TRACT OR ESOPHAGUS
children, 50 mg/kg 1
hr before procedure
GASTROINTESTINAL AND
GENITOURINARY TRACT SURGERY
AND INSTRUMENTATION
mg/kg
plus
For patients
unable to take
oral medication
IM or IV ampicillin
IM or IV gentamicin
Adults, 2.0 g,
children, 50 mg/kg
given within 30 min
before procedure
1.5 mg/kg (maximal dose,
120 mg) given within 30
min before procedure plus
6 hr later
Ampicillin- and Oral clindamycin
amoxicillinallergic patients
Adults, 600 mg,
children, 20 mg/kg 1
hr before procedure
IM or IV ampicillin or oral
amoxicillin
Adults, 1 g, children, 25
mg/kg
or
Oral cephalexin[*] or
cefadroxil[*]
Adults, 2.0 g,
children, 50 mg/kg 1
hr before procedure
High-risk
IV vancomycin
patients allergic
to ampicillin and
amoxicillin
Adults, 1.0 g, children, 20
mg/kg given over 1–2 hr
plus
TREATMENT.
or
IM or IV gentamicin
Oral azithromycin or
clarithromycin
1.5 mg/kg (maximal dose,
120 mg); complete
injection/infusion within
Adults, 500 mg,
children, 15 mg/kg 1
hr before procedure
30 min before starting
procedure
Antibiotic therapy should be instituted immediately once a definitive diagnosis is made.
When virulent organisms are responsible, small delays may result in progressive
endocardial damage and are associated with a greater likelihood of severe complications..
Depending on the clinical and laboratory responses, antibiotic therapy may require
modification and, in some instances, more prolonged treatment is required. With highly
sensitive viridans group streptococcal infections, shortened regimens that include oral
penicillin for some portion have been recommended. In nonstaphylococcal disease,
bacteremia usually resolves in 24–48 hr, whereas fever resolves in 5–6 days with
appropriate antibiotic therapy. Resolution with staphylococcal disease takes longer.
Therapy of Native Valve Endocarditis Caused by Highly Penicillin-Susceptible
Viridans Group Streptococci and Streptococcus bovis
DURATION,
REGIMEN
DOSAGE[*] AND ROUTE
WK
COMMENTS
Aqueous
crystalline
penicillin G
sodium
12–18 million U/24 h IV either
continuously or in 4 or 6 equally
divided doses
4
2 g/24 h IV/IM in 1 dose
4
or
Ceftriaxone
sodium
Pediatric dose[†]: penicillin 200,000
U/kg per 24 h IV in 4–6 equally
divided doses; ceftriaxone 100 mg/kg
per 24 h IV/IM in 1 dose
Aqueous
crystalline
penicillin G
sodium
12–18 million U/24 h IV either
continuously or in 6 equally divided
doses
2
2 g/24 h IV/IM in 1 dose
2
3 mg/kg per 24 h IV/IM in 1 dose, or
3 equally divided doses
2
or
Ceftriaxone
sodium
plus
Gentamicin
sulfate[‡]
Pediatric dose: penicillin 200,000
U/kg per 24 h IV in 4–6 equally
divided doses; ceftriaxone 100 mg/kg
per 24 h IV/IM in 1 dose; gentamicin
3 mg/kg per 24 h IV/IM in 1 dose or
REGIMEN
DOSAGE[*] AND ROUTE
DURATION,
WK
COMMENTS
3 equally divided doses[‖]
Vancomycin
hydrochloride[¶]
30 mg/kg per 24 h IV in 2 equally
divided doses not to exceed 2 g/24 h
unless concentrations in serum are
inappropriately low
Pediatric dose: 40 mg/kg per 24 h IV
in 2–3 equally divided doses
4