Infective Endocarditis

Infective Endocarditis Definition

Infective Endocarditis (IE) is a type of endocarditis (swelling of the heart valves and the endocardium) caused by infectious agents like bacteria or fungi [1].

Infective Endocarditis Epidemiology

The incidence of IE ranges from 1.7-6.2 cases per 100,000 sufferers ever year [2]. Rate is higher in intravenous drug users. IE is 3 times more common in males and has a high prevalence in elderly patients. It is comparatively rare in children although its incidence may be on the rise. The incidence is low during pregnancy.

Infective Endocarditis Classification

IE is classified into various types on the basis of [3]:


The duration of persistence is considered while categorizing the disorder as:

  • Acute bacterial endocarditis (ABE) – It is possibly caused by Staphylococcus aureus and stays severe for a few days to weeks. It arises suddenly.
  • Subacute bacterial endocarditis (SBE) – It is often caused by less harmful variety of streptococci and progresses gradually over a few weeks to a few months.

Culture results

According to results obtained from cultures, it is classified as Culture-positive and Culture-negative. The latter is most commonly caused by prior administration of antibiotics.

Heart side

Based on the side of heart affected, it is differentiated into:

  • Right-sided (can result from use of narcotics or other similar drugs)
  • Left-sided (often arising in sufferers without a history of intravenous exposure)

Infection setting

This arises when the infectious organism is supposed to be transmitted in hospitals and other health care settings (healthcare associated endocarditis).

Valve type

As per which prosthetic valves are involved, it is categorized as:

  • Early prosthetic valve endocarditis (postoperative bacterial contamination or intraoperative contamination are common causes)
  • Late prosthetic valve endocarditis (community acquired microorganisms are the frequent cause)

Infective Endocarditis Symptoms

The signs may develop gradually (subacute) or rapidly (acute). It is typically characterized by fever, which persists for several days before the development of any other symptoms.

Other symptoms may involve:

  • Chills
  • Paleness
  • Abnormal color of urine
  • Blood in the urine
  • Profuse sweating
  • Joint pain
  • Fatigue
  • Muscle aches and pains
  • Night sweats (may be severe)
  • Nail problems (splinter hemorrhages under the nails)
  • Weakness
  • Weight loss
  • Swelling of legs, feet and abdomen
  • Respiratory shortness with activity
  • Red, painless spots on the skin of palms and soles (Janeway lesions)
  • Red, painful nodes (also called Osler’s nodes) in the pads of the fingers and toes

The valves that IE affects most commonly are:

  1. Mitral valve
  2. Aortic valve
  3. Combined mitral and aortic valve
  4. Tricuspid valve
  5. Pulmonary valve (rarely)

Infective Endocarditis Causes

Infective endocarditis is most often caused by:

  • Blood infection by bacteria and other infectious agents (during dental processes etc.)
  • Streptococcus viridians, responsible for half of all cases of bacterial endocarditis, and Staphylococcus aureus and enterococcus
  • Undelying valve problems or heart disease
  • Candida, serratia and pseudomonas

Infective Endocarditis Risk Factors

The following factors increase the susceptibility to IE:

  • Artificial heart valves
  • History of rheumatic heart disease
  • Heart valve problems (such as mitral insufficiency)
  • Congenital heart disease (patent ductus arteriosus, atrial septal defect etc.)

Infective Endocarditis Diagnosis

A physical exam is performed to detect clinical features such as a possibly enlarged spleen and splinter hemorrhages in the fingernails. Abnormal heart sounds, or murmurs, may be detected with a stethoscope.

Other diagnostic tests may involve:

  • Chest x-ray
  • CT scan of the chest
  • Blood culture and sensitivity (to spot bacteria)
  • Complete blood count (may reveal mild anemia)
  • Erythrocyte sedimentation rate (ESR)
  • Echocardiogram (ultrasound of the heart)
  • Transesophageal echocardiogram

Eye exam investigations may reveal Roth’s spots (retinal bleeding). Arthritis is generally asymmetric in subacute IE and as many as 3 joints are affected.

In 2.5–31% of all cases of IE, diagnosis is often delayed due to negative blood cultures.

Infective Endocarditis Diagnostic Criteria

The Modified Duke criteria for IE diagnosis involve:

Major criteria

These include:

  • Positive blood culture for IE
  • Evidence of endocardial involvement

Minor criteria

These include:

  • Broad-range PCR (16S)
  • Microbiological phenomena
  • Predisposition to intravenous drug use or some heart disorder
  • Fever: Body temperature higher than 38°C
  • Vascular phenomena: mycotic aneurysm, septic pulmonary infarcts, major arterial emboli, Janeway’s lesions, conjunctival haemorrhages and intracranial haemorrhage.
  • Immunological phenomena: Osler’s nodes, rheumatoid factor, glomerulonephritis and Roth’s spots.
  • Echocardiogram findings, which are consistent with IE but do not satisfy a major criterion

Infective Endocarditis Differential Diagnosis

This involves distinguishing IE symptoms from those of:

  • Autoimmune disorders
  • Chronic infection
  • Malignancy
  • SLE
  • Vasculitis
  • Rheumatological disorders
  • Antiphospholipid syndrome
  • Atrial myxoma and other cardiac neoplasms
  • Lyme disease
  • Polymyalgia rheumatica
  • Reactive arthritis

Infective Endocarditis Treatment

Those requiring intravenous antibiotics need hospitalization. Prolonged, high-dose antibiotic treatment is required for bacterial removal. Antibiotics are usually administered for 4-6 weeks, based on the particular form of bacteria. Blood tests can help physicians chose the right antibiotic. Damaged heart valves may need replacement by surgery.

Earlier, anticoagulants were used for treatment of IE. The use of anticoagulation agents is a matter of debate today (possible risk of neurological complications).

Empiric therapy is not generally used in suspected cases of subacute endocarditis until blood cultures identify the etiology [4].

In people with a prior history of IE, continued medical follow-up is recommended for better management.

Infective Endocarditis Prognosis

When treated early, the outcome is good. If undiagnosed and untreated timely, heart valves may suffer damages. Prognosis also depends on rate of cure and mortality.

Infective Endocarditis Complications

The possible complications include:

  • Brain abscess
  • Jaundice
  • Glomerulonephritis
  • Congestive heart failure
  • Stroke
  • Mitral valve regurgitation (MR) or Mitral valve stenosis
  • Severe valve damage
  • Neurological changes
  • Rapid or irregular heartbeats, including atrial fibrillation
  • Blood clots or emboli that travel to brain, abdomen kidneys or lungs

Infective Endocarditis Prevention

The preventive measures include:

  • Preventive antibiotics , recommended by The American Heart Association, for individuals susceptible to IE before some dental procedures and surgeries on infected skin, respiratory tract etc.
  • Non-use of intravenous drugs
  • Using a fresh needle for each injection
  • Using alcohol pads before injecting

Infective Endocarditis ICD9 Code

The ICD9 codes for this disorder are 421.0 and 420.1.


Infective Endocarditis (

Infective Endocarditis (Wikipedia)

Infective Endocarditis Empiric Therapy (Medscape)

Image Source Joshua Abbas


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