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Bacterial Endocarditis : Definition, Causes, Sign, Symptoms, Diagnosis and Treatment

Saturday, August 11th 2012. | Bacteria, Disease, Lungs Health

Bacterial Endocarditis

Infective endocarditis remains a serious disease. This is an inflammation caused by infection of the endocardium and heart valves primarily. This inflammation is the cause of these deformities, valves that are no longer able to ensure their role in cardiac contraction.

This disease primarily affects the left heart to know the mitral and aortic valves. Intravenous drug abuse is the cause of infectious endocarditis of the right heart which now account for nearly 15% of endocarditis.  The average age of onset is between 50 and 60. 
This disease remains serious despite access to treatment Antibiotics.

Endocarditis (img thanks to metrohealth.org)

Bacterial Endocarditis

Bacterial Endocarditis Causes

Endocarditis usually develops from a congenital or acquired valvular abnormality but also on a prior heart prosthesis in place for serious valve problem.

This injury allows adhesion of platelets and fibrin which are then colonized by germs usually streptococci or some strains of enterococci of digestive origin. Endocarditis may also occur in the absence of valvular lesions.

Vegetations and ulcerations will then develop on the valves concerned: according to their importance it is possible to see valve perforations but also providing quick ejections cardiac consequences serious.

In the presence of vegetation, more frequent on the aortic valves, the risk of septic embolism websites as carriers of germs is a possible complication.  local abscesses particularly in coronary arteries and insertion areas of the heart valves are Possible. 
The front door is suspected or confirmed in more than two thirds of cases. It is in order of frequency dental, digestive, skin and urological.

The frequency of endoscopies and gestures as vascular invasive cardiac catheterization and prosthetics and stents do increase the risk of endocarditis.

Bacterial Endocarditis Patient Feels

If symptoms of infective endocarditis appear conventional diagnosis is often difficult to confirm the person usually carries a known valvular abnormality sometimes not present: fever, chills, joint and muscle pain, night sweats with fast enough asthenia (tiredness). These are signs of infection reached.

It also has other signs indicating this time a left cardiac given the preferential localization of the left heart endocarditis sweat with a more or less breathlessness, effort and at rest, persistent cough, an irregular or fast heart rate also favored by fever.

Signs of right heart failure in cases of infringement of the right heart valves (tricuspid and pulmonary) with lower limb edema, enlarged liver (hepatomegaly) and turgescence of the jugular veins seen at the base of the neck.

Bacterial Endocarditis Diagnosis

Two tests can confirm the diagnosis: ultrasound and blood cultures 
Echocardiography conventional trans thoracic improved the diagnosis of infective endocarditis but trans esophageal echocardiography allows diagnosis finer and more accurate localization of valvular and extra valves.

The esophageal route allows: 

  • To specify the extent of the lesions and in particular abscess    
  • Abetter view of the vegetation especially small 
  • To visualize the perforations of the valves and rupture of the ropes holding the valves.

The Doppler will better appreciate the importance of a leak in a valve, heard on auscultation, including a prosthesis or to identify a fistula. On prosthetic valves, ultrasound shows an abnormal movement of rocking of the prosthesis during an avulsion at the attachment ring.   resonance imaging (MRI) with gadolinium may allow the diagnosis small abscesses, escaping ultrasound. The cine-MRI can visualize communication between the abscess cavity and a heart chamber The current prostheses are consistent with the achievement of this review. blood cultures .

Practised on two different samples are usually positive blood cultures. Streptococci represent more than half of the organisms isolated. Enterococci (Enterococcus faecalis, faecium) and Streptococcus bovis are present in 23.5% of cases, viridans group streptococci (Streptococcus sanguis, mitis, salivarius, mutans, oralis, etc..) In 27% of cases.Staph germs represents one quarter. Slightly more than one patient out of 10 can have negative blood cultures, but the seed is indicated in nearly half of cases either by serology or by culture prosthetic materials hacek endocarditis group (Haemophilus, Actinobacillus in partiulier ), Gram-negative bacilli represent a small percentage of all endocarditis. In prosthetic endocarditis, Staphylococcus aureus is the organism most commonly involved (30%) followed by streptococci.

Bacterial Endocarditis Diagnosis Criteria

These criteria are known to make the diagnosis 

  • Pathologic criteria: presence of microorganisms in culture or histology in a vegetation or intracardiac abscess 
  • Vegetations or intracardiac abscess confirmed by histologyClinical criteria: 2 major or 1 major and three minor or five minor. Major criteria with positive blood cultures in a typical germs infective endocarditis in two separate donations ;
  1. Streptococcus viridans, Streptococcus bovis group hacek,
  2. Staphylococcus aureus or enterococci in the absence of a primary focus
  • Positive repeatedly with a germ consistent with infective endocarditis 
  • Blood cultures more than 12 hours apart 
  • Three / three or a majority of four or more positive blood cultures (with at least 1 hour difference between the first and last) 
  • Oscillating intracardiac mass on a valve, pillar, rope, on the implanted material, or in the direction of a jet of regurgitation in the absence of an alternative anatomic explanation 
  • Abscess
  • Appearance of a partial dehiscence a prosthetic valve or appearance of a new valvular regurgitation (worsening or changing an existing breath is not sufficient) Minor criteria - cardiac predisposition or drug user Temperatures above 38 ° C - vascular events: arterial embolism, Septic pulmonary infarction, mycotic aneurysm, intracerebral hemorrhage, - immunological Events: glomerulonephritis, Osler nodes, Roth spots. - Echocardiography compatible but with no major signs of endocarditis.

Bacterial Endocarditis Evolution

Involvement of heart valves is responsible for a rapid heart failure is the main complication of infective endocarditis. The loss of tightness of the valve may have different causes: perforation, tear, rollover valve, rupture of rope. The appearance of a conduction disorder intra cardiac (heart’s electrical system) is also a cardiac complication requiring emergency intervention. Neurological complications can also occur at the waning of endocarditis: They are related to the occurrence of an embolism of the lesions on the valves and a carrier of germs and usually manifested by hemiplegia or hemiparesis. These emboli whose gravity is real are more frequent in prosthetic endocarditis.   More vegetations are large on ultrasound, the greater the risk of embolism is high.

Bacterial Endocarditis Treatment

The main treatment of endocarditis is based on intravenous antibiotics administered over long periods. This treatment is often long and difficult because the lesions containing the seeds are hard to reach: it often involves a combination of antibiotics chosen after laboratory tests. It is practiced on a drip in hospital with a biological monitoring and cardiology, echocardiography allows him to monitor very precisely the evolution of lesions.

Early diagnosis will occur before the lesions are large and the choice of antibiotics will be widely facilitated if a germ has been identified in blood cultures.

In heart failure or non control of infectious endocarditis on the plan that is inefficient antibiotic intervention is indicated for changing the valve and damage to a prosthetic valve.

This intervention is urgent, in a specialized center, under extracorporeal circulation: it is burdened with many complications.  For prosthetic endocarditis, medical treatment, tailored to germs, is often insufficient in itself and replacement of the prosthesis is the only solution.

After surgical treatment, antibiotics will be continued for six weeks.  Abscesses are usually treated surgically.

Finally the treatment of endocarditis on pacing (pace maker) based on medical treatment, associated the withdrawal of the probe can be difficult because embedded in the myocardium is sometimes necessary to perform surgical removal, in any case preferable to facing large vegetations.

Bacterial Endocarditis Prevention

In people at high risk of endocarditis, any situation that could cause the introduction of bacteria into the blood poses a risk of infection.

In the presence of a congenital heart defect that was repaired, or a mechanical prosthetic valve, or a heart murmur is not labeled, see your doctor whether you should take antibiotics before undergoing dental procedures to reduce the risk of heart infection. This advice also goes for other interventions, whether benign as endoscopy or heavier. Your doctor will advise you on how to reduce your risk by using antibiotics before these procedures, in order to prevent infection. The risks associated with prophylactic antibiotics outweigh the benefits. These risks include adverse reactions to antibiotics ranging from mild to potentially serious, and the emergence of antibiotic resistant bacteria.

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