INTRODUCTION — People who are at increased risk of infections of the heart valves (a condition called infective endocarditis [IE]) need to take an antibiotic before certain dental or other invasive medical procedures. Taking a preprocedure antibiotic to prevent infection is called "antibiotic prophylaxis."

Although IE is relatively uncommon, it can happen if bacteria get into your bloodstream (for example, during a dental or surgical procedure) and travel to your heart. This can lead to serious problems.

This topic will discuss the benefits and risks of antibiotics taken to prevent IE as well as who might need these antibiotics and when. Your health care provider can talk to you about your situation and whether you are a candidate for preventive antibiotics.

INFECTIVE ENDOCARDITIS — Infective endocarditis (IE) is an infection of the lining of heart chambers or valves (figure 1). It is usually caused by bacteria. It occurs most commonly in people who have abnormal or artificial heart valves; less commonly, it can also occur in otherwise healthy people with normal heart valves.

IE develops following a sequence of events:

●Bacteria enter the bloodstream and can then stick to the lining or valves of the heart, usually at a site of previous injury or abnormality as the blood circulates through the chambers of the heart.

●The bacteria then grow and form a small mass (called a "vegetation") on the heart valves or lining. The valve or surface that is infected can then become damaged.

IE can lead to serious problems, such as heart failure or kidney damage. If a piece of a mass (vegetation) in the heart breaks off, it may also block blood vessels in the brain, causing a stroke or damage other internal organs by impairing their blood supply.

IE can develop in a very small percentage of people who undergo dental or other medical procedures that can cause bacteria (for example, normally present in the mouth or on the skin) to gain access to the bloodstream. American Heart Association guidelines on who should receive preventive antibiotics have evolved over the years. Most experts believe that taking antibiotics before selected dental procedures has benefit (which outweighs the risk of antibiotics) only for people who are at highest risk of adverse outcome from IE. Your health care provider can help you understand your risk of developing IE; whether you might benefit from preventive antibiotics or whether the risk of an adverse effect of an antibiotic may outweigh its benefit.

People at highest risk — Preventive antibiotics before certain procedures are generally recommended for people who are considered to be at highest risk of adverse outcome from IE, including those with the following conditions:

●A prosthetic heart valve or past valve repair with prosthetic (man-made) materials

●A prior history of IE

●Certain types of congenital heart disease

●Cardiac transplantation with presence of heart valve abnormalities

Procedures that require preventive antibiotics are listed below. (See 'Situations that might require preventive antibiotics' below.)

People with some other heart problems are considered to be at moderate or low risk for IE; although preventive antibiotics were recommended for people at moderate risk in the past, this is no longer the case in most situations as the risk of taking an antibiotic may outweigh benefit in certain types of patients.

What do antibiotics do? — Antibiotics kill bacteria. They are useful in treating many different types of bacterial infections, including IE. In some situations, they can also help prevent bacterial infections from developing in the first place.

However, there are downsides to antibiotic overuse, which is why antibiotics to prevent IE are only recommended in certain cases (see 'People at highest risk' above). Antibiotics can cause side effects such as nausea, vomiting, diarrhea, and infection of the colon by a bacteria called Clostridioides difficile; it is also possible to develop an allergy to an antibiotic, even if you have taken it before without issue. In addition, on a larger scale, overuse of antibiotics contributes to antibiotic resistance. This happens when bacteria that have been exposed to an antibiotic change so that the drug no longer works against them. Infections caused by antibiotic-resistant bacteria are more difficult to treat and can be dangerous or even deadly.

General dental care — Anyone who is at risk of developing IE should follow a program of good oral hygiene and tooth care. This includes a professional cleaning every six months, twice-daily tooth brushing, and daily flossing. These measures can help to prevent plaque and bacteria from building up around the gums and teeth and reduce the risk of developing IE.

SITUATIONS THAT MIGHT REQUIRE PREVENTIVE ANTIBIOTICS — The following treatment suggestions come from the American Heart Association's guidelines on preventive antibiotics.

Dental procedures — People who are at highest risk for infective endocarditis (IE) (see 'People at highest risk' above) should take one dose of an antibiotic before certain dental, oral, or upper respiratory tract procedures. For these people, preventive antibiotics are recommended for routine dental cleanings as well as more invasive procedures such as tooth extractions, abscess drainage, or root canals.

Antibiotics are usually given by mouth (as pills or liquid), although it can be given by injection if you are unable to take oral medications. Several different antibiotics can be used for prophylaxis; your doctor will choose one based on your situation (eg, people with a penicillin allergy need to take a nonpenicillin drug).

Antibiotics are generally not needed prior to getting anesthetic injections, dental X-rays, or orthodontic appliances. In addition, people who have had a prior joint replacement are not considered to be at highest risk for IE and do not require antibiotics prior to dental or other invasive procedures, unless they have other relevant risk factors. (See 'People at highest risk' above.)

Upper respiratory procedures — People at highest risk for IE generally need preventive antibiotics before selected invasive procedures involving the upper respiratory tract (including the throat). These include procedures that involve incisions, such as surgery on the tonsils or adenoids, or biopsy (removal of a tissue sample for testing).

Skin or soft tissue procedures — People at highest risk for IE should get preventive antibiotics if they need a procedure to treat infection of the skin or soft tissue. Examples include biopsy of an infected area or draining of an abscess.

SITUATIONS THAT GENERALLY DO NOT REQUIRE PREVENTIVE ANTIBIOTICS — Antibiotics are no longer routinely recommended in the following situations, even in people at highest risk for infective endocarditis (IE).

Genitourinary or gastrointestinal procedures — The American Heart Association does not consider surgeries or procedures on the digestive or urinary system to have a high risk of causing IE. This includes colonoscopy, sigmoidoscopy, cystoscopy, and many other procedures.

Pregnancy — Pregnant women who are at highest risk for IE (see 'People at highest risk' above) should follow the same guidelines as people who are not pregnant and take an antibiotic before certain dental, oral, or upper respiratory tract procedures.

WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Mitral regurgitation (The Basics)

Patient education: Mitral valve prolapse (The Basics)

Patient education: Tetralogy of Fallot (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Group B streptococcus and pregnancy (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Antithrombotic therapy in patients with infective endocarditis
Antimicrobial prophylaxis for the prevention of bacterial endocarditis
Antimicrobial therapy of left-sided native valve endocarditis
Antimicrobial therapy of prosthetic valve endocarditis
Candida endocarditis and suppurative thrombophlebitis
Complications and outcome of infective endocarditis
Clinical manifestations of Staphylococcus aureus infection in adults
Culture-negative endocarditis: Epidemiology, microbiology, and diagnosis
Clinical manifestations and evaluation of adults with suspected left-sided native valve endocarditis
Native valve endocarditis: Epidemiology, risk factors, and microbiology
Infections involving cardiac implantable electronic devices: Epidemiology, microbiology, clinical manifestations, and diagnosis
Right-sided native valve infective endocarditis
Pathogenesis of vegetation formation in infective endocarditis
Prosthetic valve endocarditis: Epidemiology, clinical manifestations, and diagnosis
Role of echocardiography in infective endocarditis
Surgery for left-sided native valve infective endocarditis
Surgery for prosthetic valve endocarditis

The following organizations also provide reliable health information.

●National Library of Medicine

     (www.nlm.nih.gov/medlineplus/endocarditis.html)

●National Heart, Lung, and Blood Institute

     (www.nhlbi.nih.gov/)

●American Heart Association

     (www.heart.org/)