Patients at highest risk — Prophylaxis was recommended only in those settings associated with the
highest risk of developing an adverse outcome if IE was to occur. Patients with the following cardiac
conditions were considered to meet this criterion:


Prosthetic heart valves, including bioprosthetic and homograft valves.
Prosthetic material used for cardiac valve repair
A prior history of IE.
Unrepaired cyanotic congenital heart disease, including palliative shunts and conduits.
Completely repaired congenital heart defects with prosthetic material or device, whether placed
by surgery or by catheter intervention, during the first six months after the procedure.
Repaired congenital heart disease with residual defects at the site or adjacent to the site of the
prosthetic device.
Cardiac "valvulopathy" in a transplanted heart. Valvulopathy is defined as documentation of
substantial leaflet pathology and regurgitation.


No longer indicated — Common valvular lesions for which antimicrobial prophylaxis is no longer
recommended in the 2007 AHA guidelines include bicuspid aortic valve, acquired aortic or mitral valve
disease (including mitral valve prolapse with regurgitation), and hypertrophic cardiomyopathy with latent or
resting obstruction.

Procedures that may result in transient bacteremia — The 2007 AHA guidelines recommend that
antimicrobial prophylaxis be given to patients with the cardiac lesions cited above when they undergo
procedures likely to result in bacteremia with a microorganism that has the potential ability to cause
endocarditis.

Dental — The risk of IE is generally considered to be the highest for all dental procedures that involve
manipulation of either gingival tissue or the periapical region of teeth or perforation of the oral mucosa.

All individuals at risk for developing IE should establish and maintain a program of oral health care including
regular professional care, the regular use of manual or powered toothbrushes, dental floss, and other
plaque removing devices.

Respiratory tract — Although a variety of organisms may cause bacteremia during respiratory tract
procedures, there is no direct evidence that such bacteremias cause IE. The AHA guideline does not
recommend routine antimicrobial prophylaxis for procedures unless they involve incision or biopsy of the
respiratory tract mucosa. Examples of such procedures include tonsillectomy, adenoidectomy, or
bronchoscopy with biopsy.

In patients who undergo an invasive respiratory tract procedure as part of the treatment of an established
infection:


•The ongoing antibiotic regimen should include an agent that is active against viridans group streptococci.
•In patients who have a respiratory tract infection that is known or suspected to be caused by
Staphylococcus aureus, the regimen should include an agent active against S. aureus.

Genitorurinary and gastrointestinal tracts — The risk of bacteremia is significantly lower for invasive
genitourinary (GU) procedures such as dilation of strictures, insertions of catheters, and prostatectomy
compared with dental or respiratory tract infections. Invasive gastrointestinal (GI) procedures, such as lower
bowel endoscopy with biopsy or endoscopic retrograde cholangiopancreatography, have an even lower risk
of IE since bacteremia due to organisms capable of causing endocarditis occurs in less than 5 to 10 percent
of cases.

The AHA guidelines no longer consider any GI (including diagnostic colonoscopy or
esophagogastroduodenoscopy) or GU procedures high risk
and therefore do not recommend
routine use of IE prophylaxis even in patients with the highest risk cardiac conditions defined above.

Some patients with established infections of the GI or GU tract may have enterococcal bacteremia. For
patients with the highest risk cardiac conditions who have ongoing GI or GU tract infection or who are
undergoing a procedure for which antibiotic therapy to prevent wound infection or sepsis is indicated, the
AHA suggests an antibiotic regimen that includes an agent active against enterococci.

For those patients with an enterococcal urinary tract infection or colonization scheduled to undergo elective
cystoscopy or urinary tract manipulation, eradication of the organism prior to the procedure should be
attempted.

Vaginal or cesarean delivery — Vaginal or cesarean delivery is not an indication for routine antibiotic
prophylaxis since the rate of bacteremia with these procedures is low. The 2007 AHA guidelines specify that
prophylaxis is not indicated for vaginal delivery or cesarean section, and the 2008 AHA/ACC guidelines note
that antibiotic prophylaxis is not recommended for genitourinary procedures.

The American College of Obstetrics and Gynecology (ACOG), Committee on Obstetic Practice has
endorsed the 2007 AHA recommendations, noting that infective endocarditis prophylaxis is not
recommended for vaginal or cesarean delivery in the absence of infection. In patients with the highest risk
lesions with established infection that could cause bacteremia (such as chorioamnionitis or pyelonephritis)
the underlying infection should be treated in the usual fashion; treatment should include an intravenous
regimen effective for infective endocarditis prophylaxis.

The 2008 ACC/AHA guidelines for management of adults with congenital heart disease contain
antibiotic prophylaxis recommendations that generally agree with the 2007 AHA prophylaxis guidelines.
However, the 2008 ACC/AHA adult congenital heart disease guidelines include a recommendation that is it
reasonable to consider antibiotic prophylaxis against infective endocarditis before vaginal delivery at the
time of membrane rupture in select patients with the highest risk of adverse outcomes. This includes
patients with prosthetic cardiac valve or prosthetic material used for cardiac valve repair and patients or
unrepaired or palliated cyanotic heart disease, including surgically constructed palliative shunts and
conduits. However, proof of efficacy of prophylaxis in this setting is not available.

Skin or musculoskeletal tissue — Patients with infected skin, skin structure, or musculoskeletal tissue
may have polymicrobial infections. When such patients undergo a surgical procedure, only bacteremia with
staphylococci or beta-hemolytic streptococci are likely to cause IE. The appropriate antibiotic regimen is
discussed below. (See 'Special circumstances' below.)

CHOICE OF ANTIMICROBIAL AGENT — Among the selected patients for whom antimicrobial prophylaxis is
suggested, the antimicrobial regimen recommended by the AHA guidelines varies with the procedure being
performed.

Dental, oral, or upper respiratory tract procedures — The primary antibiotic regimen for most patients,
including those with prosthetic valves, is amoxicillin, 2 g orally 30 to 60 minutes before the procedure; a
second dose is not necessary.

A different regimen is warranted in the following circumstances; all drugs are given 30 to 60 minutes before
the procedure:


•Patients who are allergic to penicillins or ampicillin can be treated with cephalexin (2 g) or azithromycin or
clarithromycin (500 mg) or clindamycin (600 mg).
•Patients who are unable to take oral medications can be treated with 2 g of intravenous or intramuscular
ampicillin. Patients allergic to penicillin can be given cefazolin or ceftriaxone (1 g intravenously) OR 600 mg
of intravenous or intramuscular clindamycin.

Genitourinary or gastrointestinal procedures — For those high risk patients who undergo
gastrointestinal or genitourinary procedures at a time of ongoing gastrointestinal or genitourinary infection,
antibiotic coverage for enterococcal bacteremia should be provided with amoxicillin or ampicillin or, in the
patient unable to tolerate these drugs, vancomycin. (See "Antibiotic prophylaxis for gastrointestinal
endoscopic procedures" and 'Procedures that may result in transient bacteremia' above.)

Skin and musculoskeletal tissue — Although infection of the skin or musculoskeletal tissue is often
polymicrobial, only staphylococcal or beta-hemolytic streptococcal bacteremia is likely to cause endocarditis
in such circumstances. Thus, an antistaphylococcal penicillin or a cephalosporin is appropriate (table 1). In
patients undergoing procedures involving infected skin and musculoskeletal tissue (eg, incision and
drainage of skin abscess), the treatment regimen should include drugs active against these organisms.
Clindamycin or vancomycin may be used when the patient is unable to take a beta-lactam or is known or
suspected to have an infection caused by a methicillin-resistant staphylococcus. (See "Skin abscesses,
furuncles, and carbuncles".)

Pregnancy — As noted above, uncomplicated vaginal or cesarean delivery is not a routine indication for
antibiotic prophylaxis although prophylaxis may be considered in certain circumstances (see 'Vaginal or
cesarean delivery' above).

If antibiotic prophylaxis is given to prevent enterococcal endocarditis, amoxicillin, ampicillin, and vancomycin
are appropriate agents and they should be administered at the time of delivery.

Children — Children given endocarditis prophylaxis should receive the same antibiotic regimens and
dosing intervals as noted above. Equivalent pediatric doses for oral therapy are as follows:


•Amoxicillin — 50 mg/kg to a maximum dose of 2 g
•Azithromycin or clarithromycin — 15 mg/kg to a maximum dose of 500 mg
•Clindamycin —20 mg/kg to a maximum dose of 600 mg
•Cephalexin — 50 mg/kg to a maximum dose of 2 g

Equivalent pediatric doses for intramuscular or intravenous therapy are as follows:


•Ampicillin — 50 mg/kg to a maximum dose of 2 g
•Cefazolin or ceftriaxone — 50 mg/kg to a maximum dose of 1 g
•Clindamycin — 20 mg/kg to a maximum dose of 600 mg
•Vancomycin — 15 mg/kg to a maximum dose of 1 g
Antibiotic Prophylaxis