Endocarditis Enterococcal

Enterococcal endocarditis is a serious infection of the heart’s inner lining and valves caused by Enterococcus bacteria, particularly Enterococcus faecalis. This condition primarily affects elderly and fragile patients and requires prolonged antibiotic treatment to prevent life-threatening complications.

Table of contents

• What is Enterococcal Endocarditis?
• Causes and Risk Factors
• Symptoms
• Diagnosis
• Treatment
• Outlook and Complications

What is Enterococcal Endocarditis?

Endocarditis is a life-threatening inflammation of the inner lining of the heart’s chambers and valves, called the endocardium. When this condition is caused by Enterococcus bacteria, it is called enterococcal endocarditis^[1].

Enterococci are a unique type of bacteria that can survive in many different environments and resist many common antibiotics. They normally live in the human body, particularly in the mouth, digestive system, and on the skin^[1].

Enterococcus bacteria account for approximately 10 to 15 percent of all cases of infective endocarditis, which is endocarditis caused by germs. Among Enterococcus species, Enterococcus faecalis is responsible for about 90 percent of enterococcal endocarditis cases^[1][3][5].

When bacteria enter the bloodstream and reach the heart, they attach to damaged heart tissue and grow into clumps called vegetations. These growths contain bacteria, fibrin (a protein involved in blood clotting), and tiny cell fragments called platelets. As inflammation continues, the vegetations break down the surrounding heart tissue, which can severely damage the heart valves^[1][6].

Causes and Risk Factors

Enterococcal endocarditis occurs when Enterococcus bacteria enter the bloodstream and settle on the heart. Research shows that Enterococcus faecalis can colonize the undamaged inner surface of blood vessels and produce strong biofilms, which are protective layers that help bacteria survive^[1].

The bacteria can enter the bloodstream in several ways. Sometimes this happens during dental or medical procedures that break the skin or other tissue. Even activities like brushing teeth can introduce bacteria into the blood, especially in people with gum disease^[2][8].

Certain factors increase the risk of developing enterococcal endocarditis. Elderly patients and those with weakened health are particularly vulnerable. The condition generally affects an elderly and fragile population with a high mortality rate^[3].

Other important risk factors include^[2][6][8]:

• Artificial heart valves or heart valve disease
• Previous history of endocarditis
• Heart conditions present at birth (congenital heart disease)
• Implanted cardiac devices like pacemakers or defibrillators
• Use of intravenous drugs
• Indwelling catheters (tubes that stay in blood vessels for long periods)
• Recent heart surgery
• Hemodialysis for kidney failure
• Weakened immune system
• Poor dental hygiene

Enterococci emerge with similar frequency in both hospital-acquired and community-acquired infections, comprising about 15 to 18 percent of cases in each setting^[8].

Symptoms

Symptoms of enterococcal endocarditis can vary from person to person. The condition may develop slowly over weeks or months, or it can begin suddenly with severe symptoms^[2].

Common symptoms affecting the heart and breathing include^[2][7]:

• Chest pain, especially when breathing
• Shortness of breath
• Fast heart rate
• A new or changed whooshing sound in the heart (heart murmur)

General symptoms often include^[2][7]:

• Fever above 100°F (38.4°C)
• Chills and night sweats
• Fatigue
• Muscle and joint aches
• Loss of appetite and unexplained weight loss

Less common symptoms can include^[2][7]:

• Blood in the urine
• Swelling in the feet, legs, or belly
• Painless red, purple, or brown flat spots on the soles of the feet or palms of the hands (Janeway lesions)
• Painful red or purple bumps on the tips of the fingers or toes (Osler nodes)
• Tiny purple, red, or brown round spots on the skin, in the whites of the eyes, or inside the mouth
• Tenderness under the left rib cage

If you have symptoms of endocarditis, see your healthcare provider as soon as possible, especially if you have a heart condition or other risk factors^[2][7].

Diagnosis

Diagnosing enterococcal endocarditis requires careful evaluation including a thorough history and physical examination^[8].

The most important diagnostic test is blood testing. Healthcare providers must demonstrate the presence of bacteria in the blood to confirm the diagnosis. Multiple blood samples are typically taken from different sites to identify the specific type of bacteria causing the infection^[8].

Echocardiography is another essential diagnostic tool. This ultrasound examination of the heart creates images that can show vegetations on the heart valves and assess damage to the heart^[8].

Additional tests may include:

• Electrocardiogram (ECG) to check heart rhythm
• Chest X-ray
• Other imaging tests if complications are suspected

Healthcare providers use specific diagnostic criteria that combine clinical findings, blood test results, and imaging findings to confirm the diagnosis^[8].

Treatment

Treatment of enterococcal endocarditis is a continuing challenge due to the bacteria’s resistance to many commonly used antibiotics^[3].

Enterococci are partially resistant to many antimicrobial agents such as penicillin and ampicillin, and show high-level resistance to most cephalosporins (a class of antibiotics) and sometimes carbapenems (another class of antibiotics). This occurs because of special proteins in the bacteria that reduce antibiotic effectiveness^[3][12].

Treatment requires prolonged courses of antibiotics, often lasting several weeks. International guidelines suggest treating fully penicillin-susceptible strains with amoxicillin combined with either gentamicin or ceftriaxone^[5].

Recent studies have found that patients treated with combination therapy using gentamicin had better outcomes than those treated with antibiotics alone. However, there is concern about the potential kidney damage (nephrotoxicity) from aminoglycoside antibiotics like gentamicin, particularly as many patients with enterococcal endocarditis are elderly^[5].

For patients with strains resistant to multiple antibiotics, treatment options become more limited. Vancomycin may be substituted for penicillin in some cases, but resistance to vancomycin is becoming an increasing problem^[4][10].

In some cases, surgery may be necessary in addition to antibiotic treatment. Surgery might be needed to repair or replace damaged heart valves^[2].

Adequately powered clinical trials are needed to determine the optimal treatment for enterococcal endocarditis, as current evidence is limited^[5].

Outlook and Complications

Enterococcal endocarditis is a serious condition with a high mortality rate. The long-term outlook remains poor despite modern medical advances, with mortality ranging from 11 to 35 percent^[4][5].

Without quick treatment, endocarditis can damage or destroy the heart valves. The infection can force the heart to work harder to pump blood, and sometimes the heart cannot pump out enough blood^[2][11].

Complications can be serious and sometimes life-threatening^[6]:

• Heart failure
• Kidney damage
• Stroke
• Blood clots (emboli) that travel to other organs
• Enlarged and painful spleen
• Damage to fingers and toes
• Lung problems

The vegetations can break into small pieces and travel through the bloodstream to other parts of the body, blocking blood vessels and causing damage to vital organs^[6].

These harmful effects may enable the bacteria to survive as an unrecognized infection in people without symptoms, potentially providing a source for future clinical episodes of endocarditis^[1].

With quick, aggressive treatment including antibiotics and sometimes surgery, many people can survive. However, without treatment, endocarditis can be fatal^[6].