What Is Endocarditis?

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Endocarditis is a rare condition affecting the lining of the heart chambers and valves, that can either be infectious or non-infectious. It is usually caused by a bacteria or fungus entering the bloodstream which then infects the inner lining of the heart (the endocardium) in areas that are vulnerable to infection, causing inflammation.  It is absolutely critical to speak to a healthcare professional if you develop any of the symptoms of endocarditis, especially if you possess any of the factors that make you more susceptible to the condition. The majority of people recover from Endocarditis, but it can be fatal if not treated early and so quick medical intervention is essential. 

In the 19th century, endocarditis was first described by Jean Corvisart, a French physician, who used the term ‘vegetations’ to describe the abnormalities seen in autopsies of patients who had died from endocarditis. Throughout the years,  scientists continued their research  and a  medicinal cure for endocarditis was discovered in 1945, when Lowe et al. used penicillin to treat 7 bacterial endocarditis patients.

Several progressions were made in how to determine a diagnosis thereafter, the most notable being the development of the Duke criteria, a set list of major and minor symptoms that accurately help to pinpoint the diagnosis of infective endocarditis.  

The remainder of this article shall discuss the common causes of endocarditis, how it is treated and will answer some commonly asked questions. 

Causes of endocarditis

Endocarditis has two causes  - infective and non-infective. Infective endocarditis is often referred to as bacterial endocarditis because it is most commonly  triggered by a bacterial (or fungal) infection that enters the bloodstream and settles in the heart lining, a heart valve or blood vessel.  These areas of the heart are often already damaged and so are more susceptible to infection. 

Common ways that bacteria or fungi can reach the heart include: 

  • Through the mouth; seemingly innocuous activities that we all take part in on a daily basis such as eating food and brushing our teeth can sometimes result in bacteria entering the bloodstream. Keeping teeth and gums healthy helps to reduce the risk because if damaged, it’s easier for bacteria to enter the body.  Although it is rare, dental procedures such as tooth extractions can trigger endocarditis
  • Through existing infection: bacteria can spread from a pre-existing infection such as a skin infection to the heart
  • Through needles and medical instruments; medical procedures that involve equipment entering the body always carry a risk that bacteria might be introduced to the blood. Injecting drugs can also allow bacteria to be introduced to the body. Amongst drug users, most endocarditis infections result from not using sterile needles and syringes. 

 80%  of infective endocarditis cases are caused by streptococci or staphylococci bacteria. 

Non-infective endocarditis, often referred to as non-bacterial thrombotic endocarditis (NBTE) is much rarer than the infective form. Sterile clots form on heart valves and endocardium tissue and as with infective endocarditis, it is more likely to affect damaged heart areas.   It is more likely to be diagnosed after death than infective endocarditis, and causes include:

  • Existing malignancies, particularly mucinous adenocarcinoma2
  • Mechanical stress on the heart
  • Chemical agents 
  • Immunological factors such as post-rheumatic disease
  • Imbalance of blood coagulation; this can occur during pregnancy and during whole-body infections when blood can clot too easily 

Libman-Sacks endocarditis is a form of non-infective endocarditis sometimes seen in patients with existing systemic lupus erythematosus, the most common form of the autoimmune condition Lupus.

Signs and symptoms of endocarditis

Symptoms can appear very quickly over a few days (acute endocarditis). Some cases may appear over several weeks or even months (subacute endocarditis). 

Initially, endocarditis symptoms are often similar to that of flu: 

  • High temperature
  • Muscle and joint aches
  • Body chills
  • Headache
  • Fatigue

If treatment is not accessed at this early stage of infection, heart valves can become damaged which results in blood flow around the body being restricted. 

Other symptoms include:1

  • Cough
  • Shortness of breath
  • Night sweats
  • Small red, brown, purple spots on the skin
  • Narrow red lines of blood under the nails
  • Painful or painless red lumps on pads of fingers and toes
  • Confusion
  • Lack of appetite and weight loss

It’s important to note that some of the symptoms, such as the red spots might be harder to see on darker skin tones. 

Management and treatment for endocarditis

Treatment for infective endocarditis will most likely require hospital admission. Here, you will be given intravenous antibiotics with the aim of killing the bacteria in the early stages of the infection. 

If your symptoms improve, you may be asked to continue your antibiotics at home for up to six weeks. During this time it’s essential to have regular appointments with your doctor to ensure that the treatment is working as it should.

Antibiotics are prescribed if the endocarditis is caused by bacteria. If caused by a fungus, antifungal medications are administered in a similar way. 

If endocarditis causes damage to your heart, you may need to have surgery. The damage will be spotted during tests such as an ECG and echocardiogram. Surgery might be necessary if:

  • Your tests suggest that you have suffered heart failure
  • Your high temperature continues despite treatment
  • A drug resistant bacteria/fungi has caused your condition
  • You have developed blood clots
  • You have an artificial heart valve
  • Your tests show that an abscess or fistula has developed inside your heart

The aims of surgery are to repair damage to the heart. Sometimes the damage is so great to the heart valves that it will be necessary to replace them with artificial/prosthetic valves. Draining pus from any abscess and repairing a fistula may also occur during surgery if necessary. 


How is endocarditis diagnosed?

It can be hard to diagnose endocarditis because the symptoms often mimic other conditions such as viral infections but there are procedures to carry out to form a diagnosis:

  • Blood cultures (blood tests) to find out what type of bacteria is causing inflammation
  • An echocardiogram to look for damage to the heart, this is a painless procedure where an ultrasound scan looks at the structure of your heart
  • An electrocardiogram (ECG), this is another painless procedure whereby electrodes are stuck to your body to gain a ‘trace’ of the rhythm of your heart
  • A chest x-ray to look for fluid in your lungs 
  • An MRI scan of your heart 

Heart failure and stroke are complications that can occur with endocarditis and according to the British Heart Foundation, if medical professionals suspect that you may have endocarditis, sometimes treatment is started before they are certain that you have the condition because if left untreated, it can be fatal.

How can I prevent endocarditis?

In some cases, it is necessary to prescribe antibiotics to prevent the development of endocarditis. This doesn’t happen often but might be necessary if you are due to have a medical procedure whereby the risk of bacteria entering your blood may be higher. Using antibiotics in this way is known as prophylactic antibiotic use. It may also be necessary for antibiotics to be used before and after dental procedures for those that are most at risk.   Overuse of antibiotics can cause antibiotic resistance and so it’s important to weigh up the benefits and risks with your healthcare professional. 

Other simple ways to lower the risk of endocarditis include: 

  • Practicing good hygiene e.g. washing hands before eating
  • Adhering to very good dental hygiene practices and having regular dentist check ups
  • Avoid tattoos and body piercings
  • Do not take drugs
  • Take care with any cuts and grazes, making sure they are clean to prevent skin infection

Being aware of the symptoms of endocarditis and taking quick action if you spot them is the best way to prevent critical illness with the infection. This is especially important if you are more at risk of developing it. 

Who is  at risk of endocarditis?

Infective endocarditis affects those assigned male at birth more often than those assigned female at birth. All races and ethnicities appear to be affected equally. The average age of onset is around 50 years of age but it can occur in all ages. 

You are more at risk if:

  • You have had previous heart surgery to repair/replace damaged heart valves
  • You have HIV
  • You are a drug user
  • You have invasive dental procedures
  • You have had endocarditis previously 
  • You are exposed to healthcare facilities/healthcare workers regularly
  • You have mitral valve leakage
  • You have had rheumatic fever resulting in abnormal cardiac valve function

How common is endocarditis?

In the UK, endocarditis is considered a rare condition, even amongst those with the highest number of risk factors. However, as medicine advances, it is becoming more common because there are more individuals receiving surgery to replace heart valves or to treat congenital heart defects. 

When should I see a doctor?

If you have any symptoms of endocarditis you should see your doctor straight away. Although for most people the symptoms are not likely to be caused by endocarditis, it is important to rule it out. For those that are at a higher risk of endocarditis, this is especially important. 


Endocarditis can be infective or non infective. Infective endocarditis is more common and has much more literature available to study. 

Symptoms may begin as mild flu-like symptoms but need to be addressed straight away as complications of the condition include heart failure and stroke. 

The condition is most often caused by bacteria entering the bloodstream which then affects the endocardium. Those at risk of the condition include those that inject drugs and those that have previously had heart surgery. 

Treatment for the condition includes prompt antibiotic administration and surgery is sometimes needed to repair damage to the heart. 

Although it is a rare condition, it is very important to get rapid medical intervention if endocarditis is suspected. 


  1. Bussani R, DE-Giorgio F, Pesel G, Zandonà L, Sinagra G, Grassi S, et al. Overview and comparison of infectious endocarditis and non-infectious endocarditis: a review of 814 autoptic cases. In Vivo. 2019;33(5):1565–72. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6755013/
  2. Huang A, Yang Y, Shi JY, Li YK, Xu JX, Cheng Y, et al. Mucinous adenocarcinoma: A unique clinicopathological subtype in colorectal cancer. World J Gastrointest Surg [Internet]. 2021 Dec 27 [cited 2023 Jul 4];13(12):1567–83. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8727185/
  3. Ibrahim AM, Siddique MS. Libman sacks endocarditis. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Mar 22]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK532864/

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Jessica Gibson

Bachelor of Science- BSc(Hons)- Health Sciences- The Open University

Jessica is a Health Sciences graduate with a passion for both Science and English and is delighted to have found a way to combine the two. She is a motivated and enthusiastic writer determined to make scientific information more widely accessible.
Jessica is especially interested in infectious diseases, neurodegenerative diseases, the impact of trauma on physical health, health equity and the health of children residing in developing nations.

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