eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Endocarditis, Bacterial

Brian Keith Eble, MD, Assistant Professor of Pediatrics, Section of Cardiology, University of Arkansas for Medical Sciences, Arkansas Children's Hospital
Gerardo Reyes, MD, Clinical Assistant Professor, Department of Pediatrics, University of Illinois at Chicago; Director of Pediatric Critical Care Outreach and Development, Midwest NeoPed Associates, Ltd
Contributor Information and Disclosures

Updated: Dec 10, 2008

Introduction

Background

Bacterial endocarditis is a microbial infection of the endothelial surface of the heart. Signs and symptoms of bacterial endocarditis are diverse; therefore, the practitioner must have a high degree of suspicion to make an early diagnosis. In addition, classification that implicates the temporal aspect, etiology, anatomic site of infection, and relevant pathogenic risk factors is essential in therapeutic and prognostic considerations.

Pathophysiology

A high-velocity flow through a stenotic or incompetent valve or an abnormal communication between systemic and pulmonary circulations causes turbulence downstream from the opening. This turbulence damages or denudes the endothelium, to which platelets and fibrin adhere, and a small, sterile" nonbacterial thrombotic endocardial lesion" forms. In addition, indwelling intravascular catheters in the right heart may directly traumatize the endocardium or valvular endothelium. Circulating bacteria and inflammatory cells adhere to and grow in these thrombi, forming an infected vegetation. Infection may occur (1) on the wall, where the turbulent jet strikes, or (2) downstream, near the orifice, where the flow eddies. Once vegetation forms, the constant blood flow may result in embolization to virtually any organ in the body. A brisk immunologic response is produced.

Frequency

United States

The incidence of endocarditis is approximately 1 case per 1000 pediatric hospital admissions. This incidence has remained essentially unchanged over the past 40 years; however, the distribution of etiologies has shifted. Rheumatic heart disease, which was once common, is now a rare cause of endocarditis. In contrast, the advent of sophisticated cardiac procedures and early intervention has led to an increase in the incidence of endocarditis in children with congenital heart disease. Preexisting cardiac abnormalities are found in approximately 75-90% of children with bacterial endocarditis.

Mortality/Morbidity

The overall mortality rate for endocarditis in pediatric patients is approximately 16-25%. Improved general health care, improved dental care, early treatment, and antibiotic prophylaxis have decreased the mortality rate. Mortality is mostly due to secondary congestive heart failure (CHF).

Factors that increased the risk of complications include prosthetic valve endocarditis, left-sided endocarditis, infection with Staphylococcus aureus or fungi, previous endocarditis, cyanotic congenital heart disease, systemic-to-pulmonary shunts, and a poor response to antibiotic therapy.

Race

No racial predilection is observed.

Sex

No predilection for either sex is noted.

Age

Bacterial endocarditis is most frequently observed in adults, but the incidence in children with congenital heart disease or central indwelling venous catheters continues to rise.

Clinical

History

Features of bacterial endocarditis are due to bacteremia, local cardiac invasion by organisms, peripheral embolization, and the formation of immune complexes.

• Patients with bacterial endocarditis may present with many nonspecific symptoms; however, 85-99% of patients are febrile. Patients with congenital heart disease and fever require special consideration.
• Other historical features include fatigue, chills, sweats, anorexia, malaise, a cough, a headache, myalgia and/or arthralgia, and confusion.
• Patients with acute bacterial endocarditis present with an acute, toxic, febrile illness and symptoms that have lasted less than 2 weeks. A history of intravenous (IV) drug use may be elicited. S aureus is the most common cause of acute bacterial endocarditis.
• Patients with subacute bacterial endocarditis present with a more nonspecific flulike illness and symptoms that have lasted more than 2 weeks. Subacute bacterial endocarditis is more common in patients with an underlying congenital heart defect.

Physical

Physical findings are nonspecific and vary. Factors such as the duration of illness, microbiologic etiology, and patient's age may vary.

• Fever is present in 85-99% of patients with endocarditis. Fever is usually low grade with a temperature rarely exceeding 39°C that is remittent and is typically not associated with rigors.
• A new or changing heart murmur is noted in 20-80% of patients. These murmurs may be difficult to identify in patients with subacute endocarditis or in infants and young children who may already have a clinically significant murmur secondary to congenital heart disease.
• Neurologic abnormalities occur in approximately 30-40% of patients and are most frequent in endocarditis caused by S aureus. Symptoms include stroke, intracerebral hemorrhage, and subarachnoid hemorrhage.
• Peripheral symptoms may be observed.
  • Extracardiac manifestations of endocarditis are less common in children than in adults. Petechiae are the most common of these symptoms (20-40%). They are found on the palpebral conjunctiva, the buccal or palatal mucosa, and the extremities. However, petechiae are not specific for endocarditis.
  • Splinter and subungual hemorrhages are dark red, linear streaks in the nail beds of the fingers and toes.
  • Osler nodes are small, tender, subcutaneous nodules that develop in the pulp of the digits.
• Acute heart failure may be due to valve destruction or distortion and/or rupture of the chordae tendineae. Chronic heart failure may be due to progressive valvular insufficiency with worsening ventricular function. Heart failure with aortic insufficiency is associated with high mortality rates.
• Hepatosplenomegaly is noted in approximately 15-20% of patients.
• Renal insufficiency, as a result of immune complex–mediated glomerulonephritis, occurs in less than 15% of patients with endocarditis and may cause hematuria but rarely azotemia.
• In neonates, endocarditis commonly produces septic embolic phenomena, such as osteomyelitis, meninigitis, and pneumonia. Neonates with endocarditis may also have feeding problems, respiratory distress, tachycardia, or neurologic symptoms.
• The diagnosis of endocarditis with the modified Duke criteria is based on pathologic or clinical findings.¹ Pathologic criteria for definite infectious endocarditis include microorganisms on cultures or histology in a vegetation or histologic confirmation of active disease in a vegetation or intracardiac abscess. Clinical criteria for definite infectious endocarditis includes 2 major, 1 major and 3 minor, or 5 minor criteria, as follows:
  • Major criteria
    • Positive blood cultures (2 separate cultures for a typical endocarditis microorganism, such as Streptococcus viridans or HACEK organism [Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus paraphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, or Kingella species], persistently positive blood cultures, or evidence of infection with a Coxiella organism and/or Q fever)
    • Positive echocardiographic findings (eg, oscillating mass and/or vegetation, paravalvular abscess, or dehiscence of a prosthetic valve)
    • New valvular regurgitation
  • Minor criteria
    • Predisposition (history of IV drug use or congenital heart disease)
    • Fever with a temperature of more than 38°C
    • Vascular phenomena (arterial emboli, septic pulmonary infarcts, intracranial hemorrhage, conjunctival hemorrhage, Janeway lesions [painless, hemorrhagic lesions on palms and soles])
    • Immunologic phenomena (glomerulonephritis, Osler nodes, Roth spots, positive result for rheumatoid factor)
    • Positive blood culture findings without meeting the criteria above or serologic evidence of active infection consistent with endocarditis

Causes

Risk factors for bacterial endocarditis may be divided into those associated with high-risk conditions and those from high-risk procedures.

• High-risk conditions
  • Congenital heart disease (septal defects, valve disease, cyanotic heart disease)
  • Acquired valve disease
  • Prosthetic valve
  • IV drug use
  • Previous episode of bacterial endocarditis
  • Surgical systemic to pulmonary shunts and conduits
  • Central venous catheters
• High-risk procedures (procedures that are likely to produce bacteremia involving typical microorganisms in susceptible patients)
  • Dental procedures (extractions, implants, root canals)
  • Respiratory procedures (tonsillectomy and adenoidectomy, surgical operations, bronchoscopy)
  • GI procedures (sclerotherapy, biliary tract surgery, endoscopic retrograde cholangiopancreatography [ERCP])
  • Genitourinary tract (prostatic surgery, cystoscopy, urethral dilation)
• Microbiology
  • A select group of organisms causes most cases of endocarditis. Gram-positive organisms, particularly alpha-hemolytic streptococci (S viridans), S aureus, and coagulase-negative staphylococci, are the most common offenders.
  • Enterococci are rare but dangerous causative organisms because they often are highly resistant to antibiotic treatment.
  • Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella species (HACEK organisms) are particularly common in neonates and immunocompromised children.
  • Fungal endocarditis is a severe disease with poor prognosis. Complications are common.
• Culture-negative endocarditis occurs when a patient has typical clinical or echocardiographic findings of endocarditis, with persistently negative blood cultures. Common causes include recent antibiotic therapy or infection caused by a fastidious organism that grows poorly in vitro.

References

• Acute Lymphoblastic Leukemia
• Acute Myelocytic Leukemia
• Arthritis, Septic
• Endocarditis, Fungal
• Fever in the Toddler
• Fever in the Young Infant
• Heart Failure, Congestive
• Kawasaki Disease
• Meningitis, Bacterial
• Myocarditis, Nonviral
• Pneumonia
• Rheumatic Fever
• Vasculitis and Thrombophlebitis