Patient information: Antibiotics before procedures (Beyond the Basics)

INTRODUCTION

Many people are told that they need to take an antibiotic before having a dental, surgical, or other invasive medical procedure. This topic discusses the benefit of taking a pre-procedure antibiotic, who should take antibiotics, as well as an explanation of when antibiotics are usually recommended.

Certain procedures, such as a root canal or tooth extraction, may allow bacteria from the mouth to enter the bloodstream. Rarely these bacteria can infect the heart valves and lining of the heart, causing them to become inflamed. This inflammation is called infective endocarditis. Infective endocarditis has the potential to cause catastrophic medical problems, including heart failure and leakage of the heart valves.

When taken before a procedure, antibiotics may prevent bacteria from being released into the bloodstream. This is known as antibiotic prophylaxis.

INFECTIVE ENDOCARDITIS

Infective endocarditis (IE) is an infection of the lining of heart chambers or valves with bacteria, fungi, or other organisms. IE occurs most commonly in people who have abnormal heart valves or had previous heart surgery; less commonly, it can occur in otherwise healthy people who have do not have heart disease (see 'Guidelines for antibiotic prophylaxis' below).

Infective endocarditis develops following a sequence of events:

• Bacteria circulate in the bloodstream and stick to the lining or valves of the heart, usually at a site of previous injury or surface irregularity or abnormality.
• The bacteria then grow on the valve surface, forming a small mass (called a vegetation) on the heart valves or lining. The valve or surface that is infected may then become secondarily damaged.

IE can develop in a very small percentage of people who undergo dental or other medical procedures that can cause bacteria to be transiently released into the bloodstream. Antibiotics are commonly given to people undergoing dental procedures who have preexisting heart murmurs or known problems with their heart valves, although the evidence that these antibiotics are always necessary or effective is not conclusive. Some studies show that antibiotics can help to prevent IE while others show no benefit.

Guidelines for antibiotic prophylaxis — In the past, American Heart Association guidelines recommended that most patients with a heart murmur receive antibiotics prior to almost any dental procedures, even minor ones. However, these guidelines have changed considerably over time as more information has become available about the actual risk of dental procedures for patients with heart conditions. Review of studies performed between 1950 and 2006 which included thousands of patients has shown that there was no benefit of using preventive antibiotics, except in the highest risk patients [1].

Highest risk — People with the following conditions are considered to be at the highest risk of developing infective endocarditis. Preventive antibiotics are generally recommended for people with the following conditions before certain procedures:

• A prosthetic heart valve
• Valve repair with prosthetic material
• A prior history of infective endocarditis
• Many congenital (from birth) heart abnormalities, such as single ventricle states, transposition of the great arteries, and tetralogy of Fallot, even if the abnormality has been repaired. Patent foramen ovale, the most common congenital heart defect, does not require prophylaxis

The list of procedures that require pretreatment with antibiotics is available below. (See 'Antibiotic recommendations' below.)

Moderate risk — People with the following conditions are considered to be at moderate risk of developing infective endocarditis. Antibiotic prophylaxis is NOT generally recommended for people with moderate risk conditions. This is an important change from prior recommendations [1].

• Valve repair without prosthetic material
• Hypertrophic cardiomyopathy
• Mitral valve prolapse with valvular regurgitation and/or valvular thickening
• Most other congenital cardiac abnormalities not listed above
• Unrepaired ventricular septal defect, unrepaired patent ductus arteriosus
• Acquired valvular dysfunction (eg, mitral or aortic regurgitation or stenosis)
• Atrial septal defect, ventricular septal defect, or patent ductus arteriosus that was successfully closed (either surgically or with a catheter based procedure) within the past six months

Low risk — People with the following conditions are thought to have a low risk of infective endocarditis. Antibiotics have never been recommended for people with these conditions:

• Physiologic, functional, or innocent heart murmurs
• Mitral valve prolapse without regurgitation or valvular leaflet thickening
• Mild tricuspid regurgitation
• Coronary artery disease (including previous coronary artery bypass graft surgery)
• Simple atrial septal defect
• Atrial septal defect, ventricular septal defect, or patent ductus arteriosus that was successfully closed (either surgically or with a catheter based procedure) more than six months previously
• Previous rheumatic fever or Kawasaki disease without valvular dysfunction
• People with pacemakers or defibrillators

Dental care recommendations — Anyone who is at risk of developing infective endocarditis should follow a program of careful mouth and tooth care. This includes a professional cleaning every six months, twice daily tooth brushing, and once daily flossing. These measures can help to prevent plaque and bacteria from building up around the gums and teeth.

ANTIBIOTIC RECOMMENDATIONS

The following treatment suggestions come from the American Heart Association's guidelines on antibiotic prophylaxis.

Dental, oral, or upper respiratory tract procedures — People who are at HIGHEST risk for IE (see 'Highest risk' above) should take one dose of an antibiotic by mouth (pills or liquid) one hour before certain dental, oral, or upper respiratory tract procedures; a second dose is not necessary.

• People allergic to penicillin — People who are allergic to penicillin can be treated one hour before the procedure with an alternate antibiotic.
• People unable to take oral medications — People who are unable to take oral medications can be treated with an antibiotic injection 30 minutes before the procedure.

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 infective endocarditis. This includes colonoscopy, sigmoidoscopy, cystoscopy, and many other procedures.

Antibiotics are no longer routinely recommended before these procedures, even in people with the highest risk heart conditions [1].

Pregnancy — Pregnant women who are at highest risk for IE (see 'Highest risk' above) should take an antibiotic before certain dental, oral, or upper respiratory tract procedures.

A pregnant woman who has a high risk of IE does NOT usually need antibiotic prophylaxis before a normal vaginal delivery or cesarean section. Antibiotics may be recommended before labor or cesarean section for other reasons, including prevention of complications related to group B streptococcus. (See "Patient information: Group B streptococcus and pregnancy (Beyond the Basics)".)

Children — Children with a moderate or high risk of developing infective endocarditis are usually given antibiotics before selected dental and surgical procedures.

No treatment — The guidelines provided above may not apply to every situation. There may be instances in which a person has a high or moderate risk of IE and antibiotics are not recommended. In such cases, it is important to understand the risks and benefits of taking versus not taking preventive antibiotics. You should discuss these issues with your healthcare provider before the procedure.

WHERE TO GET MORE INFORMATION

Your healthcare 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 web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare 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 information: Mitral regurgitation (The Basics)
Patient information: Mitral valve prolapse (The Basics)
Patient information: 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 information: 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.

Anticoagulant and antiplatelet therapy in patients with infective endocarditis
Antimicrobial prophylaxis for bacterial endocarditis
Antimicrobial therapy of native valve endocarditis
Antimicrobial therapy of prosthetic valve endocarditis
Candida endocarditis
Complications and outcome of infective endocarditis
Complications of Staphylococcus aureus bacteremia
Culture-negative endocarditis
Diagnostic approach to infective endocarditis
Epidemiology, risk factors and microbiology of infective endocarditis
Infections involving cardiac implantable electronic devices
Infective endocarditis in injection drug users
Infective endocarditis: Historical and Duke criteria
Pathogenesis of vegetation formation in infective endocarditis
Epidemiology, clinical manifestations, and diagnosis of prosthetic valve endocarditis
Role of echocardiography in infective endocarditis
Surgery for native valve 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/HEARTORG/)

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