Overview

Are you curious about heart health and its relation to infections? Do you or someone you know had to go through endocarditis or sepsis and want to know more about this topic? In this article, we will discuss both conditions and give an overview about their origin, symptoms and treatment.

So, what is endocarditis? Also called infective endocarditis (IE), it is described as a rare infection of the endocardium, which is the inner lining of the heart.¹ It is usually caused by bacteria or fungi that enter the bloodstream and attack the cardiac muscle.² Endocarditis can be a deadly cause of sepsis, with a mortality rate of 20-25%.³

Sepsis is the body’s reaction to an infection, rather than an infection in itself; it is a life-threatening and severe reaction that requires urgent medical attention.^4,5 Sepsis is sometimes referred to as “blood poisoning” due to the familiarity with the term, however, this is not an accurate description, and the two terms should not be used interchangeably.⁵

Origin, risk factors and pathophysiology

Endocarditis

Endocarditis was described more than 350 years ago by the French physician Lazare Rivière.³ It is described as an infection of the heart, most commonly the valves.³ Although its incidence seems to be increasing, it remains a rare, but severe cause of sepsis.³ The common causes of endocarditis include: 

• Bacterial: around 80-90% of IE cases are caused by gram-positive cocci of the Staphylococcus, streptococcus, and enterococcus species.⁶ The most frequently isolated bacterium linked to endocarditis is Staphylococcus aureus, causing up to 30% ofinfections⁶
• Fungal: infections with Candida or Aspergillus are rare, however can cause fatal IE⁶
• Other: everyday activities such as brushing teeth and eating food can allow causative agents to enter the bloodstream.⁷ Additionally, using needles or medical instruments that are contaminated can increase the risk of infection and introduce bacteria into the bloodstream, which can then lead to endocarditis⁷

In addition to causative agents, some people are at higher risk of developing endocarditis, particularly those with:⁷

• Heart valve disease
• Prosthetic valves installed
• Hypertrophic cardiomyopathy
• Congenital heart disease
• Previous history of endocarditis
• Injection of drugs

Pathophysiology of endocarditis lies in the presence of pre-existing damage or inflammation of the endothelial wall.³ After the initial damage, the second aspect is the harmful deposition of sterile fibrin-platelet aggregates in the affected areas that cause the formation of lesions known as “non-bacterial thrombotic endocarditis”.³

These lesions are ideal for the anchoring of bacteria that are present in the bloodstream, however, not all of the bacteria in the blood are capable of colonising these lesions. For example, gram-negative bacilli are vulnerable to humoral innate immune responses, while gram-positive (e.g. Staphylococcus aureus) have molecules called adhesins that allow them to interact with the endothelium, platelets and proteins of the clotting cascade.³

Lastly, these fibrin-platelet aggregates mature and grow into clumps along with a high number of bacteria organised into complex biofilms, which are known as “vegetations”.³ These vegetations can cause the bacteria to be more tolerant to antibiotics and are the hallmark of IE, as they cause continuous bacteraemia (presence of bacteria in the bloodstream) that may develop into septic metastases and cause valvular destruction.³

Sepsis

The definition of sepsis has undergone changes over the years, however, currently, it is described as a life threatening organ dysfunction that is caused by dysregulation of the body's response to infection.⁸ A subset of sepsis is septic shock, which is characterised by strong cellular, metabolic and circulatory abnormalities that lead to higher risk of mortality than sepsis alone, as well as multiorgan failure.^3,8

The causes of sepsis vary geographically and by age, however bacterial infections of the respiratory and gastrointestinal tracts are the most common.⁸ Sepsis can also be a result of fungal infections, or viruses such as COVID-19 or influenza.⁴

Like with endocarditis, a set of the population are at more risk of sepsis than others, including:⁴

• Age ≥ 65 years
• People with previous sepsis history
• Children below the age of 1
• Patients with weak immune systems, severe illness or chronic medical conditions (e.g. diabetes, cancer, lung or kidney disease)

When sepsis occurs, the localised inflammatory reaction to an infection, generated by our immune system, spills over to cause a systemic reaction (affecting the entire body).⁸ The immune response will depend on the specific pathogen and the individual’s factors (e.g. age, genetics etc).⁸

However, in cases of a weak immune system or a severe infection, the pathogen can extend to other areas of the body and damage other tissues, trigger a systemic immune response, as well as disrupt the blood flow which causes a dangerous drop in blood pressure.⁹

Symptoms and complications

Endocarditis

The most common symptoms of endocarditis include:¹⁰

• Fever
• Night sweats/chills
• Headaches
• Shortness of breath, especially while performing physical activities
• Fatigue
• Cough
• Muscle/joint ache
• Petechiae
• Red and painful lumps in the pads of the fingers/toes

It is also worth noting that endocarditis can have multiple complications such as:¹¹

• Damage to the heart valve
• Heart failure
• Stroke or heart attack
• Brain abscesses
• Seizure
• Meningitis
• Pneumonia
• Pulmonary embolism
• Kidney infection
• Splenomegaly
• Death

Sepsis

The symptoms of sepsis can be divided into symptoms in adults and children:¹²

• In adults:
  • Intense shivering/muscle pain
  • Severe breathlessness
  • Discoloured skin
  • Slurred speech/confusion
  • Not passing any urine in a day
• In kids:
  • Rapid breathing
  • Convulsions
  • Abnormally cold to the touch
  • Lethargic/difficulty waking up
  • Rash that does not fade on pressing

As mentioned previously, sepsis is a life-threatening condition. About 40% of sepsis survivors end up with ‘post-sepsis syndrome’, a syndrome characterised by long-term problems with physical and mental health, and cognition. Other complications of sepsis include:¹³

• Organ failure
• Recurrent infections
• Coagulopathy
• Cognitive and functional disability
• Neurological sequelae such as hearing loss or polyneuropathy
• Psychological sequelae such as anxiety and post-traumatic stress disorder

Diagnosis and detection

Endocarditis

Endocarditis can be tested for using:¹⁴

• Physical examination: this includes measurements of temperature, presence of nodules/lumps on finger and toe pads, or checking for heart murmurs
• Blood tests: such as blood cultures to test for specific microorganisms, erythrocyte sedimentation rate test, or C-reactive protein test
• Echocardiogram
• CT-scans: to identify any pus/abscess collections

Sepsis

Testing for sepsis includes multiple different methods as there is no single diagnostic test available. Some of the tests include:¹⁵

• Physical examination: this includes measurements of heart rate, blood pressure and breathing rate
• Urine analysis: to confirm a urinary tract infection or kidney issues
• Blood tests: multiple tests such as looking at white blood cell counts, lactic acid or markers of organ dysfunction (e.g. creatinine levels in kidney assessment, or cardiac biomarkers)

Therapy and treatment 

Endocarditis

Depending on the cause, endocarditis can be treated with the following:¹

• Antibiotics
• Surgery to fix/replace a damaged heart valve or drain any abscess that develops
• Management of complications that may occur; early intervention is the best method

Sepsis 

Treatment of sepsis is very crucial and important to avoid complications and death. Sepsis therapy includes:^16,17

• Antibiotic treatment within the first hour of arriving to the hospital
• Treatment in the intensive care unit
• Oxygen supplementation and intravenous (IV) fluids
• Supervised care by healthcare workers

Prevention and reduction of risks

When being faced with either endocarditis or sepsis and their complications, it is always best to take approaches to prevent them from happening. There are indeed certain actions we can take to lower the chances of developing these illnesses, such as good oral hygiene to lower the risk of infections and regular hand washing to prevent spreading of bacteria.¹⁸ Additionally, taking good care of chronic conditions such as diabetes and getting the recommended vaccinations to prevent infections can be of help.¹⁹

Summary

Endocarditis and sepsis are serious conditions that can be life changing. Endocarditis usually results from an infection in the blood that reaches the damaged heart muscles and valves. If left untreated this can result in drastic events such as the spreading of this infection to the rest of the body, leading to an uncontrolled infection. This can cause our immune system to react strongly and lead to sepsis or even septic shock. It is important for us to see the signs and test for them early to ensure the best outcome possible, however, prevention is the best approach of all.