What are the complications of infective endocarditis?
If not treated, endocarditis can result in several major complications.
Cerebrovascular accident and other organ damage
In endocarditis, bacteria and other organisms destroy the heart valves and adjacent structures resulting in the formation of clumps of organisms and cell fragments (vegetations) at the site of the infection. By any chance, if these clumps break loose, it can easily get access to your brain, different abdominal organs, lungs, kidneys and upper or lower extremities. Thus cerebrovascular accidents (also known as strokes) and damage to other organs or tissues in inevitable.
Spread of infections in distal sites of the body
Endocarditis is actually a great site of infection. That is why it can easily cause you to develop pockets of collected pus (abscesses) in major organs of your body (brain, kidneys, spleen or liver). These infections are very difficult to treat. Most importantly, an abscess may develop in the heart muscle itself. It may result in abnormal conduction through heart resulting in heart block. It may also cause abnormal heartbeat. Aortic root abscess usually requires surgery to treat them.
Endocarditis primarily damage your heart valves. In the long run it destroys your heart's inner lining as well as muscle layer. Your heart tries to compensate these disturbances by working harder to pump blood out of the heart and ultimately ending up in heart failure. As a result your heart can no longer pump enough blood to meet your body's needs. It is usually a chronic condition, and if untreated, is usually a fatal condition.
What are treatment options for endocarditis?
Like any other infections, the first line treatment for endocarditis is antibiotics. Usually intravenous antibiotics are used for better penetration into damaged tissues. Surgery is also required sometimes if there is severe damage of your heart valves.
The major goals of treatment for infective endocarditis (IE) are:
Eradicate the infectious agent from the thrombus and
address the complications of valvular infection.
In the acute setting the organisms are not usually known. In clinical settings, three sets of blood cultures are drawn within a few hours, and then empiric antibiotic therapy is started before culture sensitivity is done.
If the patient has congestive heart failure at admission, a sodium-restricted diet is recommended.
Early antibiotic therapy is important to reduce the risk of valvular damage. After obtaining three to five sets of blood cultures samples within an hour or so, infusion of the appropriate antibiotic regimen is instituted. Initial antibiotic choice is determined by clinical history and physical examination findings.
Antibiotic choice is also influenced by patient's valve conditions. If patient had previous valve surgery, more powerful antibiotics are used in general.
Native valve endocarditis (NVE) is treated with penicillin G and gentamicin. If patient has a history of intravenous (IV) drug use, nafcillin and gentamicin are used to cover for methicillin-sensitive staphylococci. Lastly, if the organism is found to be methicillin-resistant S aureus (MRSA), vancomycin is used instead.
Prosthetic valve endocarditis (PVE) is really difficult to treat. It may be caused by MRSA or coagulase-negative staphylococci. That is why without taking any chance, vancomycin and gentamicin are used for treatment. Rifampin is also used in treating individuals with infection of prosthetic valves. However, it should be administered with vancomycin or gentamicin to prevent the development of resistance to it.
If patient's renal function is poor, linezolid should be substituted for vancomycin.
What is the treatment option for subacute infective endocarditis?
In this case, you can wait until culture and sensitivity results are available. Here, delay in treatment usually does not increase the risk of complications.
Why intravenous antibiotic is used in infective endocarditis?
There is presence of high concentration of organisms within the vegetations of endocarditis. They reside deep within the thrombus or vegetation. There is also interference of fibrin and white cells with the antibiotic action. That is why if adequate therapeutic drug level is not achieved treatment may be of no value. For all of these reasons, intravenous bactericidal antibiotics are used for cure of valvular infection.
Orally administered antibiotics are only used for incurable valvular infections.
What are the doses and durations for treatment of infective endocarditis?
Native valve endocarditis caused by penicillin-susceptible organisms:
Penicillin G and gentamicin at 1 mg/kg every 8 hours for 2 weeks.
Another option: Short-course therapy with ceftriaxone and gentamicin for 2 weeks is effective in some patients. It is recommended for those with uncomplicated native valve endocarditis caused by sensitive organisms like S viridans.
If patient is allergic to penicillin: Vancomycin at 30 mg/kg/d IV in 2 equally divided doses for 4 weeks. The dose of vancomycin should not exceed 2 g/d.
Endocarditis caused by nonresistant enterococci, resistant S viridance should be treated as follows:
Penicillin G at 18-30 million U/d IV, either by continuous pump or in 6 equally divided doses daily, combined with gentamicin at 1 mg/kg IV every 8 hours for 4-6 weeks.
In patients who are allergic to penicillin, administer vancomycin at 30 mg/kg/d in 2 equally divided doses.
Six weeks of treatment is recommended for patients with symptoms of enterococcal endocarditis of more than 3 months' duration.
Infection with Enterococcus faecalis: Combination therapy with ampicillin and sulbactam or vancomycin and gentamicin is recommended.
Vancomycin-resistant Enterococcus faecalis [VRE]: They produce some of the most challenging nosocomial infections. Therapeutic options include linezolid or combination of ampicillin and imipenem.
Native valve endocarditis caused by methicillin-sensitive S aureus (MSSA):
Nafcillin or oxacillin at 2 g IV every 4 hours for 4-6 weeks.
For patients who are allergic to penicillin, vancomycin at 30 mg/kg for 4-6 weeks.
Prosthetic valve endocarditis caused by MSSA:
Nafcillin or oxacillin at 2 g IV every 4 hours for 6 weeks or longer
Cefazolin at 2 g IV every 8 hours for 6 weeks or longer
Each of these options should be combined with rifampin at 300 mg orally every 8 hours for 6 weeks and with gentamicin at 1 mg/kg IV every 8 hours for the first 2 weeks.
Prosthetic valve endocarditis caused by MRSA:
Vancomycin at 30 mg/kg for 6 weeks or longer combined with rifampin and gentamicin,
Linezolid can be considered instead of vancomycin if the patient is seriously ill. It does not need dose adjustment in patients with renal failure.
Infection by HACEK microorganisms:
Ceftriaxone at 2 g/d IV for 4 weeks
Treatment of other microorganisms:
Pseudomonas aeruginosa: Ceftazidime, cefepime, or imipenem, combined with high-dose tobramycin at 8 mg/kg/d in 3 divided doses, for 6 weeks.
For Q fever (C burnetii infection): Doxycycline combined with rifampin, trimethoprim-sulfamethoxazole, or a fluoroquinolone for 3-4 years.
Prosthetic valve endocarditis is especially difficult to treat because the microorganisms adhere to the foreign body (aortic or mitral valves) and may make them impervious to the bactericidal action of antimicrobial agents. All patients with PVE require at least 6 weeks of antimicrobial therapy. Rifampin is the key drug in the treatment option here.