Bacterial Endocarditis

How endocarditis develops

Bacteria enter the bloodstream every day, for example when brushing teeth, but the immune system clears them. Endocarditis develops when bacteria land on a surface where they can stick and grow, usually:

• a heart valve damaged by disease, scarring or wear
• an artificial (prosthetic) valve, pacemaker lead or other device
• areas of turbulent blood flow from congenital heart defects

Platelets and fibrin build up around the bacteria to form vegetations. These shield bacteria from antibiotics and the immune system, damage the valve, and can break off as emboli.

Types

Symptoms

• fever and chills, the most common sign
• fatigue, aches, night sweats and weight loss
• a new or changed heart murmur
• breathlessness and swelling from heart failure
• small red or purple spots on the skin, inside the mouth or whites of the eyes (petechiae)
• thin red-brown lines under the nails (splinter hemorrhages)
• painful red bumps on fingers or toes (Osler nodes) and painless flat spots on palms or soles (Janeway lesions)
• signs of emboli: stroke symptoms, chest pain, blood in urine, back or abdominal pain, a cold limb

Causes and risk factors

Common bacteria

• Staphylococcus aureus: skin, injection sites, IV lines, healthcare-associated infection
• Viridans group streptococci: mouth and teeth
• Enterococci: urinary and bowel sources, more common in older adults
• Streptococcus gallolyticus (bovis): linked to colon cancer, so a colonoscopy is advised when found

Risk factors

• prosthetic heart valves or valve repair with prosthetic material
• previous endocarditis
• injection drug use
• congenital heart disease, especially unrepaired cyanotic defects
• damaged valves: rheumatic heart disease, degenerative valve disease, mitral valve prolapse with leakage
• implanted devices: pacemakers and defibrillators
• long-term IV lines, hemodialysis and frequent hospital procedures
• poor dental health
• older age, diabetes and weakened immunity

Diagnosis

Endocarditis can be hard to recognize because early symptoms are vague. Doctors use the Duke criteria, which combine:

• Blood cultures: at least 2 to 3 sets taken from separate sites before antibiotics. Persistent bacteria in the blood strongly suggest endocarditis.
• Echocardiography: a transthoracic echo first, then a transesophageal echo (TEE), which is more sensitive for vegetations, abscesses and prosthetic valve infection.
• Clinical signs: fever, predisposing heart condition, emboli, immune phenomena.

Other tests include blood count, inflammatory markers, kidney function, urine tests, ECG, and CT or PET-CT scans to detect emboli or prosthetic valve infection.

Treatment

Antibiotics

• High-dose intravenous antibiotics for usually 4 to 6 weeks, chosen according to the bacteria and their sensitivities.
• Treatment starts in hospital. Some stable patients complete it with outpatient IV therapy or, in selected cases, switch to oral antibiotics.
• An endocarditis team of cardiologists, infectious disease specialists and cardiac surgeons coordinates care.

Surgery

About 40 to 50% of patients need heart surgery during treatment. Reasons include:

• heart failure from a destroyed or leaking valve
• uncontrolled infection, such as an abscess or persistent positive blood cultures
• large vegetations with high risk of emboli, or emboli already occurring
• infection with hard-to-treat organisms such as fungi
• most prosthetic valve infections

The surgeon removes infected tissue and repairs or replaces the valve. Infected pacemakers and leads are removed.

Complications

• valve destruction and heart failure
• stroke and other emboli to the brain, spleen, kidneys, lungs or limbs
• heart abscess and heart block
• kidney damage
• mycotic aneurysms (infected bulges in arteries)
• sepsis
• recurrence

Outlook

In-hospital mortality is around 15 to 20%, and higher with Staphylococcus aureus, prosthetic valves, heart failure or stroke. Early diagnosis, the right antibiotics and timely surgery improve survival. Survivors remain at higher risk of future episodes.

Prevention

• Dental hygiene: brush twice daily, floss, and see a dentist regularly. Good oral health is the most important prevention.
• Antibiotics before dental procedures are recommended only for the highest-risk groups, mainly people with prosthetic valves or valve repair material, previous endocarditis, certain congenital heart diseases, and heart transplant recipients with valve disease. Ask your cardiologist.
• Avoid injecting drugs, or use sterile equipment and harm reduction services.
• Skin care: treat skin infections promptly, and avoid tattoos and piercings in non-sterile settings.
• Hospital care: remove IV catheters when no longer needed.

Frequently asked questions

What are the first signs of bacterial endocarditis?

Early signs are often vague: fever, chills, tiredness, aches, night sweats and loss of appetite. A new heart murmur, breathlessness, tiny spots on the skin or under the nails, or stroke symptoms may follow. Anyone with a heart valve problem and unexplained fever should see a doctor.

How do you get bacterial endocarditis?

Bacteria enter the bloodstream from the mouth, skin, injection drug use, IV lines or medical procedures, and stick to damaged or artificial heart valves. People with prosthetic valves, previous endocarditis or certain heart defects are at the highest risk.

Can endocarditis be cured?

Yes, with prolonged intravenous antibiotics, and surgery when needed. However, it is serious, and complications such as valve damage, stroke and heart failure can occur. Early treatment greatly improves the outcome.

Who needs antibiotics before dental work?

Current guidelines limit preventive antibiotics to people at highest risk: those with artificial heart valves or valve repair material, previous endocarditis, certain congenital heart conditions, and heart transplant recipients with valve problems. Most people with a murmur or mitral valve prolapse do not need them.