Subacute bacterial endocarditis

Overview Of Subacute bacterial endocarditis

Subacute bacterial endocarditis (SBE) is a form of infective endocarditis that affects the inner lining of the heart, typically involving the heart valves. It is a slow-developing infection caused by bacteria that enter the bloodstream and colonize the heart's endothelial tissue. This condition primarily involves the valves of the heart, leading to inflammation and potential valve damage over time. SBE can occur when bacteria from other parts of the body, often originating from the mouth or skin, spread through the bloodstream and attach to the damaged or abnormal heart valves. While subacute bacterial endocarditis progresses more slowly than acute bacterial endocarditis, it can still result in severe complications, including heart failure, organ damage, and stroke if left untreated. The condition primarily affects individuals with pre-existing heart conditions, especially those with congenital heart defects, artificial heart valves, or a history of rheumatic fever.

Causes of Subacute bacterial endocarditis

• Subacute bacterial endocarditis is caused by bacterial infection, with several microorganisms identified as common culprits. The most frequent pathogens involved in SBE include:
• Streptococcus viridans – This group of bacteria, which is typically found in the mouth and throat, is responsible for a significant number of SBE cases. These bacteria can enter the bloodstream through activities such as dental procedures or poor oral hygiene.
• Enterococci – These bacteria are found in the intestines and urinary tract and can cause infections when they enter the bloodstream.
• Staphylococcus epidermidis – A less common cause, this bacterium typically infects individuals with prosthetic heart valves or other implanted medical devices.
• Other bacteria – In some cases, other organisms such as fungi or less common bacteria may also be responsible for causing SBE. The bacteria typically enter the bloodstream through breaches in the skin or mucous membranes, often following dental procedures, surgeries, or infections in other parts of the body, particularly the skin, urinary tract, and gastrointestinal tract.

Risk Factors of Subacute bacterial endocarditis

• Certain factors increase the risk of developing subacute bacterial endocarditis, particularly those that affect the heart or compromise the immune system. Key risk factors include:
• Pre-existing heart valve disease – Individuals with damaged or abnormal heart valves, whether from congenital defects, rheumatic fever, or previous heart surgeries, are at higher risk.
• Prosthetic heart valves – People with artificial heart valves are more prone to SBE due to the increased likelihood of bacteria adhering to the surface of the artificial valves.
• History of infective endocarditis – Those with a prior history of infective endocarditis are at increased risk for recurrence.
• Congenital heart defects – Structural abnormalities in the heart, such as a hole in the heart or malformed heart valves, increase the likelihood of developing endocarditis.
• Intravenous drug use – Sharing needles or injecting drugs can introduce bacteria directly into the bloodstream, significantly raising the risk.
• Immunocompromised states – People with weakened immune systems due to conditions like HIV, cancer treatments, or organ transplants are more vulnerable to infections.
• Poor dental hygiene or dental procedures – Bacteria from the mouth can enter the bloodstream, especially during dental work, contributing to the development of SBE.
• Diabetes – Having diabetes may impair the immune system and increase the risk of bacterial infections, including SBE.

Prevention of Subacute bacterial endocarditis

• Prevention of subacute bacterial endocarditis primarily focuses on reducing the risk of bacterial entry into the bloodstream, especially in individuals with underlying heart conditions. Key preventive measures include:
• Prophylactic antibiotics – Individuals at high risk of SBE may be prescribed antibiotics before dental or surgical procedures to prevent infection.
• Good oral hygiene – Regular brushing and flossing, along with routine dental check-ups, can help prevent bacterial infections from the mouth that might enter the bloodstream.
• Management of underlying heart conditions – Proper treatment and monitoring of pre-existing heart conditions, such as congenital defects or valve disease, can reduce the risk of SBE.
• Avoidance of intravenous drug use – Not sharing needles and seeking treatment for addiction can minimize the risk of infection through contaminated needles.
• Prompt treatment of infections – Any signs of infection, especially in individuals with heart conditions, should be promptly treated to prevent the bacteria from spreading to the heart.

Prognosis of Subacute bacterial endocarditis

• The prognosis for subacute bacterial endocarditis largely depends on early detection and appropriate treatment. When treated promptly with antibiotics, many individuals recover fully, although the condition may result in significant damage to the heart valves, necessitating lifelong monitoring or surgical valve replacement. Without treatment, SBE can be fatal due to complications such as heart failure, septic shock, or embolic events like stroke. Even with treatment, some patients may experience long-term complications, including persistent heart damage or the need for additional surgeries. For those with underlying heart conditions, the prognosis may be less favorable, and they may face ongoing cardiovascular issues.

Complications of Subacute bacterial endocarditis

• Subacute bacterial endocarditis can lead to serious complications if not treated effectively. These include:
• Heart failure – Damage to the heart valves can compromise the heart’s ability to pump blood efficiently, leading to heart failure.
• Embolism – Blood clots or infected particles can break off from the heart valves and travel to other organs, potentially causing a stroke or damage to the kidneys, lungs, or spleen.
• Septicemia – The infection can spread throughout the body, causing septic shock, which is life-threatening.
• Abscess formation – Infection can lead to the development of abscesses in various organs, complicating treatment.
• Chronic kidney disease – Embolic events or sepsis may lead to kidney damage, potentially resulting in renal failure.
• Persistent bacteremia – Some patients may experience ongoing infection despite antibiotic treatment, requiring further medical interventions.

Related Diseases of Subacute bacterial endocarditis

• Several diseases and conditions are related to subacute bacterial endocarditis, either by increasing the risk of its development or by sharing similar symptoms:
• Acute bacterial endocarditis – A more rapidly progressing form of infective endocarditis, often caused by more virulent bacteria such as Staphylococcus aureus.
• Rheumatic fever – A complication of untreated streptococcal throat infections that can lead to long-term heart valve damage, increasing the risk of endocarditis.
• Valvular heart disease – Conditions such as mitral valve prolapse, aortic stenosis, or bicuspid aortic valve, which can predispose individuals to endocarditis.
• Heart failure – Chronic heart failure may increase susceptibility to infections, including endocarditis, due to weakened heart valves.
• Vascular infections – Infections in the blood vessels, such as septic thrombophlebitis, may present with similar symptoms and complications as SBE.

Treatment of Subacute bacterial endocarditis

Treatment for subacute bacterial endocarditis typically involves a prolonged course of antibiotics, and in some cases, surgical intervention may be necessary. Key aspects of treatment include: 1. **Antibiotics** – Intravenous antibiotics are used to treat the infection, with the specific drug chosen based on the type of bacteria identified. Treatment typically lasts for 4-6 weeks. Commonly used antibiotics include penicillin, vancomycin, and gentamicin. 2. **Surgical intervention** – In cases where the heart valves are severely damaged, surgery may be required to repair or replace the affected valves. 3. **Supportive care** – Additional treatments, such as medications for heart failure, may be necessary to manage complications arising from the infection. 4. **Hospitalization** – Most patients with SBE require hospitalization for intravenous antibiotics and close monitoring of their condition. 5. **Preventive antibiotics** – Individuals at high risk for SBE may be given antibiotics before certain medical or dental procedures to prevent the infection from occurring.