Endocarditis is treated primarily with high-dose intravenous antibiotics, typically for four to six weeks, and in some cases requires open-heart surgery to repair or replace damaged valves. The specific treatment depends on which organism is causing the infection, whether the infected valve is natural or prosthetic, and whether complications like blood clots or abscesses have developed.
Why Treatment Takes So Long
Heart valve infections are notoriously difficult to clear. Bacteria or fungi embed themselves in clumps of tissue called vegetations that cling to the valve surface. Blood flow doesn’t penetrate these clumps well, so antibiotics need to reach high concentrations in the bloodstream over an extended period to kill the organisms hiding inside. That’s why treatment almost always starts with weeks of IV antibiotics delivered through a central line, often placed in a large vein near the collarbone or upper arm.
Before treatment begins, doctors draw multiple blood samples to identify the exact organism responsible. This step is critical because the type of bacteria dictates which antibiotics will work and how long treatment lasts. Results usually come back within a few days, and therapy is adjusted accordingly.
Antibiotic Treatment for Native Valves
When infection involves your own natural heart valve, the antibiotic course is generally shorter and simpler than for prosthetic valves. For streptococcal infections, which tend to be less aggressive, IV antibiotics are given for four weeks. For staph infections that respond to standard antibiotics, uncomplicated right-sided infections (the tricuspid valve, common in IV drug use) can sometimes be treated in as little as two weeks. Left-sided staph infections are more dangerous and require a full six weeks of IV therapy.
Drug-resistant staph infections (MRSA) on native valves also require six weeks of treatment, using antibiotics specifically designed to overcome that resistance.
Prosthetic Valve Infections Need More Aggressive Therapy
Infections on artificial heart valves are harder to treat because bacteria can form protective films on the prosthetic material. Treatment courses are longer, at least six weeks, and often involve combinations of two or three antibiotics given simultaneously. For staph infections on prosthetic valves, guidelines have traditionally recommended a backbone antibiotic paired with two additional drugs for the first two weeks to hit the infection from multiple angles.
That said, the evidence supporting these multi-drug combinations is weaker than many clinicians realize. A systematic review in Open Forum Infectious Diseases found that the two largest studies examining the addition of gentamicin and rifampin to standard therapy for prosthetic valve staph infections showed no clear benefit. The researchers suggested these combination recommendations should be reconsidered. Your infectious disease specialist will weigh the potential benefit against the kidney toxicity and other side effects these additional drugs can cause.
When Blood Cultures Come Back Negative
In roughly 10 to 30 percent of endocarditis cases, standard blood cultures fail to grow an organism. This can happen if you received antibiotics before cultures were drawn, or if the infection is caused by unusual bacteria that don’t grow easily in the lab. When this happens, doctors typically start empiric therapy, a broad combination of antibiotics designed to cover the most likely culprits: staph, strep, and certain gram-negative bacteria. This regimen continues for a full six weeks while additional specialized testing tries to identify the organism.
Switching to Oral Antibiotics
Spending four to six weeks tethered to an IV line is grueling, whether that happens in a hospital or at home with a visiting nurse. A landmark trial published in the New England Journal of Medicine (the POET trial) showed that switching to oral antibiotics partway through treatment works just as well as completing the entire course intravenously, provided certain conditions are met.
To qualify for the switch, you need to have been on IV antibiotics for at least 10 days (or 7 days after surgery), be clinically stable, and have an echocardiogram showing no abscess or valve problems requiring surgery. This option applies to left-sided infections caused by the most common organisms. If you’re recovering well and meet these criteria, ask your care team whether an oral switch is appropriate. It can mean the difference between weeks in a medical setting and finishing treatment at home.
When Surgery Becomes Necessary
Roughly half of endocarditis patients end up needing surgery, and the decision is often time-sensitive. Surgery is recommended when antibiotics alone can’t control the situation. The clearest triggers include:
- Heart failure from severe valve damage or leaking
- Uncontrolled infection with fevers and positive blood cultures persisting beyond five to seven days of appropriate antibiotics
- Large vegetations greater than 10 mm on the left side of the heart, particularly if embolic events (stroke, organ damage) have already occurred
- Abscess formation around the valve or invasion into surrounding heart tissue
- Prosthetic valve infection that isn’t responding to antibiotics
For right-sided infections, the threshold for surgery is higher. Vegetations need to be larger, typically over 20 mm, combined with persistent bloodstream infection or evidence of infected clots traveling to the lungs. Surgery usually involves repairing or replacing the damaged valve, removing infected tissue, and draining any abscesses.
Complications From Infected Blood Clots
One of the most dangerous aspects of endocarditis is that pieces of infected vegetation can break off and travel through the bloodstream, lodging in organs throughout the body. Where these septic emboli end up determines what additional treatment you’ll need.
In the brain, septic emboli can cause strokes or brain abscesses. Treatment depends on the size, location, and severity: some cases require interventional procedures to remove the clot, while others are managed with antibiotics alone. Stroke from endocarditis complicates surgical timing because blood thinners used during heart surgery increase the risk of bleeding in the brain.
The spleen is the second most common destination. Splenic abscesses may require surgical removal of the spleen or drainage guided by imaging, though some smaller abscesses resolve with antibiotics alone. Severe abdominal pain or sudden hemorrhage from a splenic infarct can require emergency surgery.
Fungal Endocarditis Requires Surgery
Fungal endocarditis is rare but extremely serious. Fungi like Candida and Aspergillus form biofilms on heart valves that antifungal medications struggle to penetrate. Medical treatment alone carries close to a 100 percent mortality rate.
Current guidelines recommend combining antifungal drugs with surgical removal of the infected valve within the first week for Candida infections. The antifungal course lasts six to eight weeks, followed by long-term oral antifungal medication to suppress any remaining infection. This chronic suppressive therapy may continue indefinitely, especially in patients with prosthetic valves who aren’t candidates for repeat surgery.
Monitoring During Treatment
During the first days of treatment, blood cultures are repeated every one to two days until they come back negative. Clearing the bloodstream of bacteria is one of the earliest signs that antibiotics are working. Once cultures are negative, routine repeat cultures aren’t necessary unless symptoms return or new complications develop.
Echocardiograms, typically the transesophageal type where the probe goes down your throat for a closer view of the valves, are performed at the start of treatment and repeated if your clinical picture changes. Your team will also monitor kidney and liver function regularly, since the high-dose antibiotics used in endocarditis can be hard on these organs.
Preventing Reinfection After Recovery
Once you’ve had endocarditis, you’re in the highest-risk category for getting it again. The American Heart Association recommends that endocarditis survivors take a preventive dose of antibiotics before certain dental procedures, specifically any work that involves the gums, the roots of teeth, or cutting through the lining of the mouth. Your cardiologist can provide a wallet card listing the recommended antibiotic and dose to show your dentist before any procedure.
Good oral hygiene matters more than most people realize. Daily brushing and flossing reduce the bacterial load in your mouth, lowering the number of organisms that enter your bloodstream during routine activities like chewing. Regular dental cleanings, with appropriate antibiotic prophylaxis, are an essential part of your long-term care plan.