AHA Medical/Scientific Statement
Prevention of Bacterial Endocarditis
Recommendations by the American Heart Association
Adnan S. Dajani, MD; Kathryn A. Taubert, PhD; Walter Wilson, MD; Ann F.
Bolger, MD; Arnold Bayer, MD; Patricia Ferrieri, MD; Michael H. Gewitz, MD;
Stanford T. Shulman, MD; Soraya Nouri, MD; Jane W. Newburger, MD; Cecilia
Hutto, MD; Thomas J. Pallasch, DDS, MS; Tommy W. Gage, DDS, PhD; Matthew E.
Levison, MD; Georges Peter, MD; Gregory Zuccaro, MD
Footnotes
Objective To update recommendations issued by the American Heart Association
last published in 1990 for the prevention of bacterial endocarditis in
individuals at risk for this disease.
Participants An ad hoc writing group appointed by the American Heart
Association for their expertise in endocarditis and treatment with liaison
members representing the American Dental Association, the Infectious Diseases
Society of America, the American Academy of Pediatrics, and the American
Society for Gastrointestinal Endoscopy.
Evidence The recommendations in this article reflect analyses of relevant
literature regarding procedure-related endocarditis, in vitro susceptibility
data of pathogens causing endocarditis, results of prophylactic studies in
animal models of endocarditis, and retrospective analyses of human
endocarditis cases in terms of antibiotic prophylaxis usage patterns and
apparent prophylaxis failures. MEDLINE database searches from 1936 through
1996 were done using the root words endocarditis, bacteremia, and antibiotic
prophylaxis. Recommendations in this document fall into evidence level III of
the US Preventive Services Task Force categories of evidence.
Consensus Process The recommendations were formulated by the writing group
after specific therapeutic regimens were discussed. The consensus statement
was subsequently reviewed by outside experts not affiliated with the writing
group and by the Science Advisory and Coordinating Committee of the American
Heart Association. These guidelines are meant to aid practitioners but are not
intended as the standard of care or as a substitute for clinical judgment.
Conclusions Major changes in the updated recommendations include the
following: (1) emphasis that most cases of endocarditis are not attributable
to an invasive procedure; (2) cardiac conditions are stratified into high-,
moderate-, and negligible-risk categories based on potential outcome if
endocarditis develops; (3) procedures that may cause bacteremia and for which
prophylaxis is recommended are more clearly specified; (4) an algorithm was
developed to more clearly define when prophylaxis is recommended for patients
with mitral valve prolapse; (5) for oral or dental procedures the initial
amoxicillin dose is reduced to 2 g, a follow-up antibiotic dose is no longer
recommended, erythromycin is no longer recommended for penicillin-allergic
individuals, but clindamycin and other alternatives are offered; and (6) for
gastrointestinal or genitourinary procedures, the prophylactic regimens have
been simplified. These changes were instituted to more clearly define when
prophylaxis is or is not recommended, improve practitioner and patient
compliance, reduce cost and potential gastrointestinal adverse effects, and
approach more uniform worldwide recommendations.
Endocarditis is a life-threatening disease, although it is relatively
uncommon. Substantial morbidity and mortality result from this infection,
despite improvements in outcome due to advances in antimicrobial therapy and
enhanced ability to diagnose and treat complications. Primary prevention of
endocarditis whenever possible is therefore very important.
Endocarditis usually develops in individuals with underlying structural
cardiac defects who develop bacteremia with organisms likely to cause
endocarditis. Bacteremia may occur spontaneously or may complicate a focal
infection (eg, urinary tract infection, pneumonia, or cellulitis). Some
surgical and dental procedures and instrumentations involving mucosal surfaces
or contaminated tissue cause transient bacteremia that rarely persists for
more than 15 minutes. Blood-borne bacteria may lodge on damaged or abnormal
heart valves or on the endocardium or the endothelium near anatomic defects,
resulting in bacterial endocarditis or endarteritis. Although bacteremia is
common following many invasive procedures, only certain bacteria commonly
cause endocarditis. It is not always possible to predict which patients will
develop this infection or which particular procedure will be responsible.
There are currently no randomized and carefully controlled human trials in
patients with underlying structural heart disease to definitively establish
that antibiotic prophylaxis provides protection against development of
endocarditis during bacteremia-inducing procedures. Further, most cases of
endocarditis are not attributable to an invasive procedure. The following
recommendations reflect analyses of relevant literature regarding
procedure-related endocarditis, including in vitro susceptibility data of
pathogens causing endocarditis, results of prophylactic studies in
experimental animal models of endocarditis, and retrospective analyses of
human endocarditis cases in terms of antibiotic prophylaxis usage patterns and
apparent prophylaxis failures.
The incidence of endocarditis following most procedures in patients with
underlying cardiac disease is low. A reasonable approach for endocarditis
prophylaxis should consider the following: the degree to which the patient's
underlying condition creates a risk of endocarditis; the apparent risk of
bacteremia with the procedure (as defined in these recommendations); the
potential adverse reactions of the prophylactic antimicrobial agent to be
used; and the cost-benefit aspects of the recommended prophylactic regimen.
Failure to consider all of these factors may lead to overuse of antimicrobial
agents, excessive cost, and risk of adverse drug reactions.
This statement provides guidelines for prevention of bacterial endocarditis.
It is not intended as the standard of care or as a substitute for clinical
judgment. The current recommendations are an update of those made by the
committee in 19901 and incorporate new data and include opinions voiced by
national and international experts at endocarditis meetings around the world.
Cardiac Conditions
Certain cardiac conditions are associated with endocarditis more often than
others.2 Furthermore, when endocarditis develops in individuals with
underlying cardiac conditions, the severity of the disease and the ensuing
morbidity can be variable. Prophylaxis is recommended in individuals who have
a higher risk for developing endocarditis than the general population and is
particularly important for individuals in whom endocardial infection is
associated with high morbidity and mortality.
Table 12-22 stratifies cardiac conditions into high- and moderate-risk
categories primarily on the basis of potential outcome if endocarditis occurs.
High Risk
Individuals at highest risk are those who have prosthetic heart valves, a
previous history of endocarditis (even in the absence of other heart disease),
complex cyanotic congenital heart disease, or surgically constructed systemic
pulmonary shunts or conduits.2,3 These individuals are at a much higher risk
for developing severe endocardial infection that is often associated with high
morbidity and mortality.
Moderate Risk
Individuals with certain other underlying cardiac defects are at moderate risk
for severe infection.2-4 Congenital cardiac conditions listed in the
moderate-risk category include the following uncorrected conditions: patent
ductus arteriosus, ventricular septal defect, primum atrial septal defect,
coarctation of the aorta, and bicuspid aortic valve. Acquired valvar
dysfunction (eg, due to rheumatic heart disease or collagen vascular disease)
and hypertrophic cardiomyopathy are also moderate-risk conditions.
Mitral valve prolapse (MVP) is common, and the need for prophylaxis for this
condition is controversial. Only a small percentage of patients with
documented MVP develop complications at any age.5-7 Mitral valve prolapse
represents a spectrum of valvular changes and clinical behavior.5-7 In view of
the controversy surrounding the need for prophylaxis of the individual patient
with MVP, a detailed description of the spectrum of MVP is warranted.
Normal mitral valve leaflets close at or below the plane of the mitral
annulus. This closure position is controlled by the lengths of the leaflets,
their attached chordae and papillary muscles, and the systolic size of the
ventricle. The closure position will shift beyond the annular plane toward the
left atrium, or prolapse, if the lengths of the valve apparatus, which are
constant, become too large for the size of the end-systolic ventricle, which
is variable and dynamic. Dehydration and tachycardia are common causes of
intermittent MVP. Abnormal motion of normal mitral valves is found on
echocardiographic examination in a small percentage of the adult and
adolescent ambulatory population. The high prevalence of such motion
abnormalities in young adults underscores that MVP is often an abnormality of
volume status, adrenergic state, or growth phase and not of valve structure or
function. When normal valves prolapse without leaking, as in patients with one
or more systolic clicks but no murmurs and no Doppler-demonstrated mitral
regurgitation, the risk of endocarditis is not increased above that of the
normal population.2,6,7 Antibiotic prophylaxis against bacterial endocarditis
is therefore not necessary. This is because it is not the abnormal valve
motion but the jet of mitral insufficiency that creates the shear forces and
flow abnormalities that increase the likelihood of bacterial adherence on the
valve during bacteremia.
Normal mitral valves with normal motion often have minimal leaks detectable by
Doppler examination. This does not appear to increase the risk of
endocarditis. In contrast, the regurgitation that occurs with structurally
normal but prolapsing valves originates from larger regurgitant orifices and
creates broader areas of turbulent flow. Patients with prolapsing and leaking
mitral valves, evidenced by audible clicks and murmurs of mitral regurgitation
or by Doppler-demonstrated mitral insufficiency, should receive prophylactic
antibiotics.7-11 This is supported by formal cost-benefit analysis.12
Mitral valve prolapse also occurs in the setting of myxomatous degeneration of
the mitral valve. This is a progressive disorder that has a spectrum of
manifestations.13,14 The mitral leaflets of these patients appear thickened on
the echocardiogram, due to accumulations of proteoglycan deposits.15 The
amount of thickening is variable and may increase with age.16 There is a range
of valve motion in these patients as well: they may prolapse continuously or
only with changes in heart rate or volume. Further, when prolapse occurs, it
may or may not create valvular insufficiency. In patients of any age,
myxomatous mitral valve degeneration with regurgitation is an indication for
antibiotic prophylaxis.11,17,18
Anterior mitral valve thickening is commonly found in both competent and
insufficient myxomatous mitral valves, but its presence increases the
likelihood of significant mitral regurgitation.16 Those with significant
regurgitation were older and more likely to be men.16 Other studies have shown
that male sex and age older than 45 years represent increased risk for
developing endocarditis.8,10,11,19 Patients with thickened valves that do not
leak on resting examination often develop regurgitation with exercise. These
patients with exercise-induced mitral insufficiency have been shown to
constitute a higher-risk subset for common complications (syncope, congestive
heart failure, progressive regurgitation requiring valve replacement);
endocarditis and cerebral embolic events, occurring far less frequently, were
not demonstrated to be increased in this small series.20 Men older than 45
years with MVP, without a consistent systolic murmur, may warrant prophylaxis
even in the absence of resting regurgitation.12,19
Some experts feel that an audible nonejection click even without a murmur may
identify patients with a potential for intermittent regurgitation and
therefore a risk of developing endocarditis. While there are insufficient data
on this issue, an isolated click may be an indication for more thorough
evaluation of valve morphology and function, including
Doppler-echocardiographic imaging or auscultation during maneuvers that elicit
or augment mitral regurgitation.
While children and adolescents with MVP may have the same symptoms as adults,
such as palpitations or syncope, the development of symptoms in childhood is
relatively unusual. The vast majority of children with chest pain or fatigue
do not have any form of heart disease, including MVP. Careful evaluation is
nevertheless required in children who have isolated clinical findings, such as
nonejection systolic click, since this may be the only indicator of important
mitral valve abnormality requiring prophylaxis.21 In the most recent series of
reports, MVP has emerged as an important underlying diagnosis associated with
endocarditis in the pediatric age group.3,21
A clinical approach to determination of the need for prophylaxis in
individuals with suspected MVP is given in the Figure.23
Negligible Risk
Although endocarditis may develop in any individual, including persons with no
underlying cardiac defect, the negligible-risk category lists cardiac
conditions in which the development of endocarditis is not higher than in the
general population. Whereas in pediatric patients innocent heart murmurs may
be clearly defined on auscultation, in the adult population other studies such
as echocardiography may be necessary to confirm that a murmur is innocent.
Individuals with innocent heart murmurs have structurally normal hearts and do
not require prophylaxis.
Bacteremia-Producing Procedures
Bacteremias commonly occur during activities of daily living such as routine
tooth brushing or chewing. With respect to endocarditis prophylaxis,
significant bacteremias are only those caused by organisms commonly associated
with endocarditis and attributable to identifiable procedures. The procedures
for which prophylaxis is recommended are those known to induce such
bacteremias and are discussed below. Invasive procedures performed through
surgically scrubbed skin are not likely to produce such bacteremias. Many
centers do employ periprocedure prophylaxis for transcatheter insertion of
prosthetic devices (septal occluders and vascular coils), however, although
there are no data to support the use of antibiotics in the procedures. Routine
cardiac catheterization and angioplasty do not require such precautions.
Dental and Oral Procedures
Poor dental hygiene and periodontal or periapical infections may produce
bacteremia even in the absence of dental procedures. The incidence and
magnitude of bacteremias of oral origin are directly proportional to the
degree of oral inflammation and infection.24,25 Individuals who are at risk
for developing bacterial endocarditis should establish and maintain the best
possible oral health to reduce potential sources of bacterial seeding. Optimal
oral health is maintained through regular professional care24,26,27 and the
use of appropriate dental products such as manual and powered toothbrushes,
dental floss, and other plaque-removal devices. Oral irrigator or air abrasive
polishing devices used inappropriately or in patients with poor oral hygiene
have been implicated in producing bacteremia, but the relationship to
bacterial endocarditis is unknown.24,28-31 Home-use devices pose far less risk
of bacteremia in a healthy mouth than does ongoing oral inflammation.24,28-31
Antiseptic mouth rinses applied immediately prior to dental procedures may
reduce the incidence or magnitude of bacteremia.24 Agents include
chlorhexidine hydrochloride and povidone-iodine. Fifteen milliliters of
chlorhexidine can be given to all at-risk patients via gentle oral rinsing for
about 30 seconds prior to dental treatment; gingival irrigation is not
recommended. Sustained or repeated frequent interval use is not indicated as
this may result in the selection of resistant micro-organisms.24
Antibiotic prophylaxis for at-risk patients is recommended for dental and oral
procedures likely to cause bacteremia (Table 222,24-26,28-31). In general,
prophylaxis is recommended for procedures associated with significant bleeding
from hard or soft tissues, periodontal surgery, scaling, and professional
teeth cleaning. Similarly, antimicrobial prophylaxis is recommended for
tonsillectomy or adenoidectomy. It is recognized that unanticipated bleeding
may occur on some occasions. In such an event, data from experimental animal
models suggest that antimicrobial prophylaxis administered within 2 hours
following the procedure will provide effective prophylaxis.32 Antibiotics
administered more than 4 hours after the procedure probably have no
prophylactic benefit. Procedures for which antimicrobial prophylaxis is not
recommended are also listed (Table 2).
Edentulous patients may develop bacteremia from ulcers caused by ill-fitting
dentures. Denture wearers should be encouraged to have periodic examinations
or to return to the practitioner if discomfort develops. When new dentures are
inserted, it is advisable to have the patient return to the practitioner to
correct any problems that could cause mucosal ulceration.
If a series of dental procedures is required, it may be prudent to observe an
interval of time between procedures to both reduce the potential for the
emergence of resistant organisms and allow repopulation of the mouth with
antibiotic susceptible flora. Various studies have suggested an interval of
933 to 1434 days. If possible, a combination of procedures should be planned
within the same period of prophylaxis.
Respiratory, Gastrointestinal, and Genitourinary Tract Procedures
Surgical procedures involving the respiratory mucosa may lead to bacteremia;
therefore, antimicrobial prophylaxis is recommended (Table 335-58). The use of
a rigid bronchoscope may cause mucosal damage, whereas such damage is unlikely
with a flexible bronchoscope. Endotracheal intubation per se is not an
indication for antibiotic prophylaxis.
The risk of endocarditis as a direct result of an endoscopic procedure is
small. Transient bacteremia may occur during or immediately after endoscopy;
however, there are few reports of infective endocarditis attributable to
endoscopy.35-43 For most gastrointestinal endoscopic procedures, the rate of
bacteremia is 2% to 5%, and the organisms typically identified are unlikely to
cause endocarditis.44,45 The rate of bacteremia does not increase with mucosal
biopsy, polypectomy, or sphincterotomy.46-48 There are no data to indicate
that deep biopsy, as may be performed in the rectum or stomach, leads to a
higher rate of bacteremia.
Some gastrointestinal procedures are associated with a higher rate of
transient bacteremia; for these procedures, antimicrobial prophylaxis is
recommended, particularly for patients in the high-risk category (Table 3).
Esophageal stricture dilation has been associated with bacteremia rates as
high as 45%.44 However, this number is an average result of several clinical
studies in which the rate of bacteremia ranged from 0% to 100%.49-52 In only
one study was the oropharynx the documented source of infection.52 These
studies were performed with differing methods and involved relatively small
numbers of patients. Until more data documenting the true rate of bacteremia
associated with stricture dilation become available, it is prudent to consider
this procedure as one potentially associated with an increased risk of
transient bacteremia.
The bacteremia rate associated with sclerotherapy of esophageal varices is
approximately 31%.44 Bacteremia appears to be most associated with increased
sclerosant volumes, as can occur with emergency sclerosis for active bleeding,
and with relatively longer injection needles. The bacteremia rate is lessened
with the use of shorter injection needles and sterile water.53,54 Endoscopic
ligation of varices, or banding, is not associated with increased rates of
transient bacteremia.55
An obstructed biliary tree, due to benign or malignant disease, may be
colonized with a variety of organisms. A prime risk factor for dissemination
of infection from an obstructed biliary tree is instrumentation of the
obstructed region without provision of adequate drainage. The bacteremia rates
for endoscopic retrograde cholangiography in the absence of ductal obstruction
are approximately equal to most other endoscopic procedures. Prophylaxis
should be considered primarily in cases in which biliary obstruction is known
or suspected.
In biliary tract surgery, or in any operative procedure that involves the
intestinal mucosa, there is a potential for bacteremia with organisms known to
cause endocarditis. It is therefore prudent to provide prophylaxis for
patients at high risk to develop endocarditis.
Surgery, instrumentation, or diagnostic procedures that involve the
genitourinary tract may cause bacteremia. Although the risk that any
particular patient will develop endocarditis is low, the genitourinary tract
is second only to the oral cavity as a portal of entry for organisms that
cause endocarditis. The rate of bacteremia following urinary tract procedures
is high in the presence of urinary tract infection (UTI). Sterilization of the
urinary tract with antimicrobial therapy in patients with bacteriuria should
be attempted prior to elective procedures, including lithotripsy. Results of a
preprocedure urine culture will allow the practitioner to choose antibiotics
appropriate to the recovered organisms. Procedures for which antimicrobial
prophylaxis is or is not recommended are listed in Table 3.
Many procedures involving the urethra and prostatic bed are associated with
high rates of bacteremia. The incidence of bacteremia was studied in 300
patients undergoing one of four different urologic procedures: transurethral
resection (TUR) of the prostate, cystoscopy, urethral dilation, and urethral
catheterization.56 Bacteremia was most frequent after TUR of the prostate,
occurring in 31% of the patients. In the other procedures, bacteremia occurred
in 24% following urethral dilatation, in 17% following cystoscopy, and in 8%
following urethral catheterization. Bacteremia was significantly associated
with both prostatitis on histological examination of resected prostate and
prior UTI following TUR and with prior UTI following urethral dilatation and
cystoscopy. Preexisting UTI was the major source of organisms causing the
bacteremia following TUR but was the source in only about one third of
patients following the other procedures. Enterococci and Klebsiella were the
most frequent organisms. Although bacteremia due to gram-negative bacilli is
unlikely to cause endocarditis unless a prosthetic valve is present, it may
nevertheless cause life-threatening sepsis. Therefore, an antimicrobial
regimen effective against the infective urinary pathogen, eg, enteric
gram-negative bacilli, in addition to the enterococcus, should be administered
before the invasive genitourinary procedures.
Bacteremia follows uncomplicated vaginal delivery in only 1% to 5% of
procedures, usually with various types of streptococci22; well-documented
cases of endocarditis after normal vaginal delivery are uncommon.57 Therefore,
antibiotic prophylaxis for normal vaginal delivery is not recommended. If an
unanticipated bacteremia is suspected during vaginal delivery, intravenous
antibiotics can be administered at that time. No bacteremia has been detected
in studies following cervical biopsy or manipulation of an intrauterine device
(IUD) in the absence of obvious infections.22 Bacteremia following removal of
an infected IUD is unresolved58 but would seem possible and should warrant
prophylaxis, as would other genitourinary procedures in the presence of
infection.
Prophylactic Regimens
Prophylaxis is most effective when given perioperatively in doses that are
sufficient to assure adequate antibiotic concentrations in the serum during
and after the procedure. To reduce the likelihood of microbial resistance, it
is important that prophylactic antibiotics be used only during the
perioperative period. They should be initiated shortly before a procedure and
should not be continued for an extended period (no more than 6 to 8 hours). In
the case of delayed healing, or of a procedure that involves infected tissue,
it may be necessary to provide additional doses of antibiotics for treatment
of the established infection.
Practitioners must exercise their own clinical judgment in determining the
choice of antibiotics and number of doses that are to be administered in
individual cases or special circumstances. Furthermore, because endocarditis
may occur in spite of appropriate antibiotic prophylaxis, physicians and
dentists should maintain a high index of suspicion regarding any unusual
clinical events (such as unexplained fever, night chills, weakness, myalgia,
arthralgia, lethargy, or malaise) following dental or other surgical
procedures in patients who are at risk for developing bacterial endocarditis.
Regimens for Dental, Oral, Respiratory Tract, or Esophageal Procedures
Streptococcus viridans (-hemolytic streptococci) is the most common cause of
endocarditis following dental or oral procedures, certain upper respiratory
tract procedures, bronchoscopy with a rigid bronchoscope, surgical procedures
that involve the respiratory mucosa, and esophageal procedures. Prophylaxis
should be specifically directed against these organisms. The same regimens are
recommended for all these procedures (Table 41,22,59-61). The recommended
standard prophylactic regimen for all these procedures is a single dose of
oral amoxicillin. The antibiotics amoxicillin, ampicillin, and penicillin V
are equally effective in vitro against -hemolytic streptococci; however,
amoxicillin is recommended because it is better absorbed from the
gastrointestinal tract and provides higher and more sustained serum levels.
Previously the recommended dose was 3.0 g 1 hour before a procedure and then
1.5 g 6 hours after the initial dose.1 Recent comparisons of 2.0-g and 3.0-g
dosing indicate that a 2.0-g dose results in adequate serum levels for several
hours and causes less gastrointestinal adverse effects.59 The newly
recommended adult dose is 2.0 g of amoxicillin (pediatric dose is 50 mg/kg not
to exceed the adult dose) to be administered 1 hour before the anticipated
procedure. A second dose is not necessary, both because of the prolonged serum
levels above the minimal inhibitory concentration of most oral streptococci59
and the prolonged serum inhibitory activity induced by amoxicillin against
such strains (6 to 14 hours).60 For individuals who are unable to take or
unable to absorb oral medications, a parenteral agent may be necessary.
Ampicillin sodium is recommended because parenteral amoxicillin is not
available in the United States. Individuals who are allergic to penicillins
(such as amoxicillin, ampicillin, or penicillin) should be treated with the
provided alternative oral regimens. Clindamycin hydrochloride is one
recommended alternative. Individuals who can tolerate first-generation
cephalosporins (cephalexin or cefadroxil) may receive these agents, provided
they have not had an immediate, local, or systemic IgE-mediated anaphylactic
allergic reaction to penicillin. Azithromycin or clarithromycin are also
acceptable alternative agents for the penicillin-allergic individual,61
although they are more expensive than the other regimens. When parenteral
administration is needed in an individual who is allergic to penicillin,
clindamycin phosphate is recommended; cefazolin may be used if the individual
does not have an immediate type local or systemic anaphylactic
hypersensitivity to penicillin. The previous recommendations from this
committee listed erythromycin as an alternate agent for the
penicillin-allergic patient. Erythromycin is no longer included because of
gastrointestinal upset and complicated pharmacokinetics of the various
formulations.62 Practitioners who have successfully used erythromycin for
prophylaxis in individual patients may choose to continue with this
antibiotic. The regimen is included in our previous recommendations.1
Regimens for Genitourinary and Nonesophageal Gastrointestinal Procedures
Bacterial endocarditis that occurs following genitourinary and
gastrointestinal tract surgery or instrumentation is most often caused by
Enterococcus faecalis (enterococci). Although gram-negative bacillary
bacteremia may follow these procedures, gram-negative bacilli are only rarely
responsible for endocarditis. Thus, antibiotic prophylaxis to prevent
endocarditis that occurs following genitourinary or gastrointestinal
procedures should be directed primarily against enterococci.
Table 51,22 outlines the recommended regimens for prophylaxis for
genitourinary or gastrointestinal tract procedures (excluding esophageal
procedures). The committee continues to recommend parenteral antibiotics,
particularly in high-risk patients. In medium-risk patients requiring
prophylaxis, a parenteral (ampicillin) or oral (amoxicillin) regimen is
provided. For procedures in which prophylaxis is not routinely recommended,
physicians may choose to administer prophylaxis in high-risk patients.
Specific Situations and Circumstances
Patients Already Receiving Antibiotics
Occasionally, a patient may be taking an antibiotic when coming to the
physician or dentist. If the patient is taking an antibiotic normally used for
endocarditis prophylaxis, it is prudent to select a drug from a different
class rather than to increase the dose of the current antibiotic. In
particular, antibiotic regimens used to prevent the recurrence of acute
rheumatic fever are inadequate for the prevention of bacterial endocarditis.
Individuals who take an oral penicillin for secondary prevention of rheumatic
fever or for other purposes may have viridans streptococci in their oral
cavities that are relatively resistant to penicillin, amoxicillin, or
ampicillin. In such cases, the physician or dentist should select clindamycin,
azithromycin, or clarithromycin (Table 4) for endocarditis prophylaxis.
Because of possible cross-resistance with the cephalosporins, this class of
antibiotics should be avoided. If possible, one could delay the procedure
until at least 933 to 1434 days after completion of the antibiotic. This will
allow the usual oral flora to be reestablished.
Procedures Involving Infected Tissues
Incision and drainage or other procedures involving infected tissues may
result in bacteremia with the same organism causing the infection. In
individuals at risk for endocarditis (the high- and moderate-risk categories
in Table 1), it is advisable to administer antimicrobial prophylaxis before
the procedure. Prophylaxis should be directed at the most likely pathogen
causing the infection. For nonoral soft tissue infections (cellulitis), or
bone and joint infections (osteomyelitis and pyogenic arthritis), an
antistaphylococcal penicillin or first-generation cephalosporin is an
appropriate choice. For patients who are allergic to penicillins, clindamycin
is an acceptable alternative. For those unable to take oral antibiotics or who
are known to have methicillin sodium-resistant Staphylococcus aureus
bacteremia, vancomycin is the regimen of choice. For UTI, agents active
against enteric gram-negative bacilli (such as aminoglycosides or
third-generation cephalosporins) are advisable.
Patients Who Receive Anticoagulants
Intramuscular injections for endocarditis prophylaxis should be avoided in
patients who receive heparin. The use of warfarin sodium is a relative
contraindication to intramuscular injections. Intravenous or oral regimens
should be used whenever possible.
Patients Who Undergo Cardiac Surgery
A careful preoperative dental evaluation is recommended so that required
dental treatment can be completed before cardiac surgery whenever possible.
Such measures may decrease the incidence of late postoperative endocarditis.
Patients who have cardiac conditions that predispose them to endocarditis are
at risk for developing bacterial endocarditis when undergoing open heart
surgery. Similarly, patients who undergo surgery for placement of prosthetic
heart valves or prosthetic intravascular or intracardiac materials are also at
risk for the development of bacterial endocarditis. Because the morbidity and
mortality of endocarditis in such patients are high, perioperative
prophylactic antibiotics are recommended. Endocarditis associated with open
heart surgery is most often caused by S aureus, coagulase-negative
staphylococci, or diphtheroids. Streptococci, gram-negative bacteria, and
fungi are less common. No single antibiotic regimen is effective against all
these organisms. Furthermore, prolonged use of broad-spectrum antibiotics may
predispose to superinfection with unusual or resistant micro-organisms.
Prophylaxis at the time of cardiac surgery should be directed primarily
against staphylococci and should be of short duration. First-generation
cephalosporins are most often used, but the choice of an antibiotic should be
influenced by the antibiotic susceptibility patterns at each hospital. For
example, high prevalence of infection by methicillin-resistant S aureus in a
particular inpatient unit should prompt consideration of vancomycin for
perioperative prophylaxis. It should be noted, however, that although the
majority of nosocomial coagulase-negative staphylococci exhibit the
methicillin-resistance phenotype in vitro, endocarditis prophylaxis with
first-generation cephalosporins is effective for most patients undergoing
cardiac valve surgery.63 Prophylaxis with the chosen antibiotic should be
started immediately before the operative procedure, repeated during prolonged
procedures to maintain levels intraoperatively, and continued for no more than
24 hours postoperatively to minimize emergence of resistant micro-organisms.
The effects of cardiopulmonary bypass and compromised postoperative renal
function on antibiotic levels in the serum should be considered and doses
timed appropriately before and during the procedure.
Status Following Cardiovascular Procedures
Many reparative cardiac procedures do not modify the patient's long-term risk
for infective endocarditis, which continues indefinitely (Table 1). In the
case of prosthetic valve replacement, the risk of endocarditis increases
postoperatively. In other conditions, such as closure of ventricular septal
defect or patent ductus arteriosus without residual leak, the risk of
endocarditis diminishes to the level of the general population after a 6-month
healing period. Data are insufficient to make recommendations for prophylactic
therapy after closure of these lesions by transcatheter devices. There is no
evidence that coronary artery bypass graft surgery introduces a risk for
endocarditis. Therefore, antibiotic prophylaxis is not needed for individuals
who have previously undergone this procedure. Noncoronary vascular grafts may
merit antibiotic prophylaxis for the first 6 months after implantation.
There are insufficient data to support recommendations for patients who have
had heart transplants. However, such patients are at risk of acquired valvular
dysfunction, especially during episodes of rejection. Because of this, and the
continuous use of immunosuppression in such patients, most transplant
physicians administer prophylaxis according to regimens for the moderate-risk
category
Other Considerations
A case of endocarditis, perceived as result of failure to administer a
recommended prophylactic regimen, requires careful analysis. It is important
to consider the following factors: (1) the time period between the putatively
responsible invasive procedure and the onset of clinical symptoms compatible
with endocarditis; (2) the etiologic organism causing endocarditis; (3) the
likelihood that the putative invasive procedure resulted in bacteremia; and
(4) knowledge by the patient of the presence or severity of the underlying
lesion and communication of this information to the treating physician or
dentist prior to the procedure. Most cases of procedure-related endocarditis
occur with a short incubation period of approximately 2 weeks or less
following the procedure.64 A longer incubation period between the invasive
procedure and the onset of symptoms significantly lessens the likelihood that
the procedure was the proximate cause of the endocarditis. A national registry
established by the American Heart Association in the early 1980s analyzed 52
cases of apparent failures of endocarditis prophylaxis.65 Only 6 (12%) of the
52 cases had received prophylactic regimens that were currently recommended by
the American Heart Association. The vast majority of endocarditis due to oral
organisms is not related to dental treatment procedures.24,27 One recent
large-scale, population-based, case-control study, done in 54 Philadelphia
area hospitals from 1988 to 1990, was unable to demonstrate any independent
risk for endocarditis attributable to prior dental treatment.66 In addition,
it is unlikely that cases of viridans streptococcal endocarditis would
complicate invasive nonesophageal gastrointestinal or genitourinary
procedures. Similarly, enterococcal endocarditis would be a very unusual
consequence of dental procedures.
The use of prophylactic antibiotics to prevent infection of joint prostheses
during potentially bacteremia-inducing procedures is not within the scope of
issues addressed by this committee.
Acknowledgment
The authors thank Jeanette Allison for her superb secretarial skills.
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"Prevention of Bacterial Endocarditis" was approved by the American Heart
Association Science Advisory and Coordinating Committee in October 1996, and
published in the June 11, 1997 issue of the Journal of the American Medical
Association. It is reprinted in Circulation with permission. The Council on
Scientific Affairs of the American Dental Association has approved the
statement as it relates to dentistry. The American Society for
Gastrointestinal Endoscopy has approved the statement as it relates to
gastroenterology.
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(JAMA. 1997;277:1794-1801.) (Circulation. 1997;96:358-366.)
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