71
From: Current Clinical Practice: Cardiology in Family Practice:
A Practical Guide
By: S. M. Hollenberg and T. Walker © Humana Press Inc., Totowa, NJ
3 Prevention of Bacterial Endocarditis
Bacterial endocarditis, although uncommon, is a life-threatening disease with substantial morbitity and mortality. Endocarditis usually develops in individuals with underlying structural cardiac defects who develop bacteremia with organisms likely to cause endo- carditis.
Endocarditis usually occurs after a transient bacteremia seeds either a damaged heart valve or the endocardium near anatomic defects. Although bacteremia is common following many invasive procedures, only certain bacteria commonly cause endocarditis. The risk of endocarditis depends on both the structural cardiac abnor- malities and the degree of bacteremia with the procedure, thus so preventive efforts are focused on patients with structural cardiac abnormalities. The 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 (Steckelberg & Wilson, 1993).
The incidence of endocarditis following most procedures in patients with underlying cardiac disease is low. Professional societ- ies in both the United States and Europe have formulated approaches for endocarditis prophylaxis, weighing the degree to which the patient’s underlying condition creates a risk of endocarditis, the risk of bacteremia with the procedure, and the risk–benefit ratio of the prophylactic antimicrobial regimen under consideration (Dajani et al., 1997;Horstkotte et al., 2004). In the United States, the American Heart Association (AHA) guidelines for antibiotic prophylaxis for certain patients undergoing dental, genitourinary (GU), gastrointes- tinal (GI), and respiratory procedures are the most widely followed (Dajani, 1997).
The AHA stratifies certain cardiac conditions into high, moderate, and negligible risk for developing bacterial endocarditis. This risk stratification is based on the potential outcome if endocarditis occurs (Dajani et al., 1997). Antibiotic prophylaxis is recommended for all patients in the high and moderate risk groups. Table 1 describes the cardiac conditions associated with each risk category.
Table 1
Cardiac Conditions and Endocarditis Prophylaxis Endocarditis prophylaxis recommended
High-risk category
• Prosthetic cardiac valves, including bioprosthetic and homograft valves
• Previous bacterial endocarditis
• Complex cyanotic congential heart disease (e.g., single ventricle states, transposition of the great arteries, tetralogy of Fallot)
• Surgically constructed systemic-pulmonary shunts or conduits Moderate-risk category
• Congenital cardiac malformations other than those listed in the high-risk and negligible-risk categories
• Acquired valvular dysfunction (e.g., rheumatic heart disease)
• Hypertrophic cardiomyopathy
• Mitral valve prolapse with valvular regurgitation and/or thickened leaflets
Endocarditis prophylaxis not recommended
Negligible-risk category (no greater risk than the general population)
• Isolated secundum atrial septal defect
• Surgical repair of atrial septal defect, ventricular septal defect or patent ductus arteriosus (without residua beyond 6 months)
• Previous coronary artery bypass graft surgery
• Mitral valve prolapse without valvular regurgitation
• Physiologic, functional, or innocent heart murmur
• Previous Kawasaki disease without valvular dysfunction
• Previous rheumatic fever without valvular dysfunction
• Cardiac pacemakers (intravascular and epicardial) and implanted defibrillators
Adapted from Dajani et al. (1997).
The dental procedures for which antibiotic prophylaxis is recom- mended are listed in Table 2. The respiratory, GU , and GI procedures for antibiotic prophylaxis recommendations are listed in Table 3.
For GI procedures, antibiotic prophylaxis is recommended only for patients in the high-risk category and is considered optional for the moderate-risk category.
Antibiotic therapy should be directed at the most common organ- ism associated with each medical procedures. α-Hemolytic Strepto- cocci of the viridans group is associated with procedures involving the oral, respiratory, and esophageal mucosa. The AHA now recom- mends only a single pre-procedure antibiotic dose be given for dental,
Table 2
Dental Procedures and Endocarditis Prophylaxis Endocarditis prophylaxis recommended
• Dental extractions
• Periodontal procedures, including surgery, scaling, root planing, probing, and recall maintenance
• Dental implant placement and reimplantation of avulsed teeth
• Endodontic instrumentation or surgery only beyond the apex
• Subgingival placement of antibiotic fibers or strips
• Initial placement of orthodontic bands (but not brackets)
• Intraligamentary local anesthetic injections
• Prophylactic cleaning of teeth or implants, where bleeding is anticipated
Endocarditis prophylaxis not recommended
• Restorative dentistry (operative and prosthodontic), with or without retraction cord
• Local anesthetic injections (nonintraligamentary)
• Intracanal endodontic treatment (post-placement and build-up)
• Placement of rubber dams
• Postoperative suture removal
• Placement of removable prosthodontic or orthodontic appliances
• Oral impressions, fluoride treatments, oral radiographs
• Orthodontic appliance adjustment
• Shedding of primary teeth Adapted from Dajani et al. (1997).
Table 3
Other Procedures and Endocarditis Prophylaxis Endocarditis prophylaxis recommended
Respiratory tract
• Tonsillectomy and/or adenoidectomy
• Surgical procedures that involve respiratory mucosa
• Rigid bronchoscopy Gastrointestinal tracta
• Sclerotherapy for esophageal varices
• Esophageal stricture dilation
• Endoscopic retrograde choloangiography with biliary obstruction
• Biliary tract surgery
• Surgical procedures that involve intestinal mucosa Genitourinary tract
• Prostatic surgery
• Cystoscopy, urethral dilation Endocarditis prophylaxis not recommended
Respiratory tract
• Endotracheal intubation, flexible bronchoscopy with or without biopsy
• Tympanostomy tube insertion Gastrointestinal tract
• Transesophageal echocardiographyb
• Endoscopy with or without biopsyb Genitourinary tract
• Vaginal hysterectomy or deliveryb
• Cesarean section in uninfected tissue
• Urethral catheteriztion
• Uterine dilatation and curettage
• Therapeutic abortion
• Sterilization procedures
• Insertion or removal of intrauterine devices Other procedures
• Cardiac catheterization, including balloon angioplasty
• Coronary stents and implanted pacemakers and defibrillators
• Incision or biopsy of sugically scrubbed skin
• Circumcision
aProphylaxis recommended for high-risk patients, and optional for moderate-risk.
bProphylaxis optional for high-risk patients.
Adapted from Dajani et al. (1997).
respiratory, and esphogeal procedures (Dajani et al., 1997). The rec- ommended regimen is 2 g of amoxicillin, given orally pre-procedure, a dose that has prolonged serum levels and inhibitory activity. Eryth- romycin is no longer recommended for patients with an allergy to penicillin; clindamycin, cephalexin, and cefadroxil or azithromycin should be used (Dajani et al., 1997). Enterococcus faecalis has the potential to cause bacterial endocarditis following certain GU and GI procedures. Although bacteremia with Gram-negative bacilli occurs with these procedures, endocarditis occurs only rarely. Therefore, the antibiotic regimen is geared to treating Enterococcus.Tables 4 and 5 list the prophylactic antibiotic regimens for all oral, respiratory GI,
Table 4
Endocarditis Prophylactic Regimens for Dental, Oral, Respiratory, and Esophageal Procedures
Situation Agent Regimen a
Standard general Amoxicilllin Adults: 2 g; children 50 mg/kg
prophylaxis orally 1 h before procedure
Unable to take oral Ampicillin Adults: 2 g IM or IV;
medications Children 50 mg/kg IM or IV
Within 30 min before procedure Penicillin allergic Clindamycin Adults: 600 mg; children 20 mg/kg
or orally 1 h before procedure Cefadroxilb Adults 2 g; children 50 mg/kg or
Cephalexinb Orally 1 h before procedure or
Azithromycin Adults: 500 mg; children 15 mg/kg Orally 1 h before procedure Penicillin allergic Clindamycin Adults: 600 mg; children 20 mg/kg and unable to take or IV within 30 min before procedure oral medications Cefazolin Adults: 1 g; children 25 mg/kg IM
or IV 30 min before procedure
aTotal pediatric dose should not exceed the adult dose.
bCephalosporins should not be used in patients with an immediate-type hypersensitivity reaction (urticaria, angioedema or anaphylaxis) to penicillins.
Adapted from Dajani et al. (1997).
Table 5
Endocarditis Prophylactic Regimens for Genitourinary and Gastrointestinal Proceduresa
Situation Agent Regimen
High-risk patients Ampicillin plus Adults: ampicillin 2 g IM or IV, Gentamicin plus gentamicin, 1.5 mg/kg IM
or IV (not to 120 mg), giving within 30 min of starting procedure; 6 h later, ampicillin, 1g IM or IV or amoxicillin, 1 g orallyb
Children: ampicillin, 50 mg/kg IM or IV (not to exceed 2.0 g) plus gentamicin,1.5 mg/kg, within 30 min of starting pro- cedure; 6 h later, ampicillin, 25 mg/kg IM or IV or amoxicillin, 25 mg/kg orallyb High-risk patients Vancomycin plus Adults: Vancomycin 1 g IV allergic to gentamicin over 1–2 h, plus gentamicin 1.5
ampicillin/ mg/kg IV or IM (not to exceed
amoxicillin 120 mg). Should be completed
within 30 min of starting procedureb
Children: Vancomycin 20 mg/kg IV over 1–2 h, plus gentamicin 1.5 mg/kg IV or IM; completed within 30 min of starting procedureb
(Continued on next page)
and GU procedures. All patients in the high-risk category undergoing a GU or GI procedure should receive parental antibiotics.
It is important to recognize that when endocarditis develops in individuals with underlying cardiac conditions, the severity of the disease and the ensuing morbidity can be variable. No randomized controlled trials in patients have demonstrated definitely that anti- biotic prophlaxis provides protection against procedure-induced endocarditis. In this area, as in most of medicine, adaptation of
Table 5 (Continued) Endocarditis Prophylactic Regimens for Genitourinary and Gastrointestinal Proceduresa
Situation Agent Regimen
Moderate-risk Amoxicillin or Adults: amoxicillin 2 g orally patients ampicillin 1 h before procedure, or
ampicillin 2 g IM/IV within 30 min of starting procedure Children: amoxicillin 50 mg/kg orally 1 h before procedure, or ampicillin 50 mg/kg IM/IV within 30 min of starting procedure
Moderate-risk Vancomycin Adults: vancomycin 1 g IV over
patients allergic 1–2 h completed within
to ampicillin/ 30 min of starting procedureb
amoxicillin Children: vancomycin 20 mg/kg
IV over 1–2 h; completed with 30 min of starting procedureb
aExcluding esophageal procedures.
bA second dose of vancomycin or gentamicin is not recommended.
Adapted from Dajani et al. (1997).
general guidelines to individual patients is necessary. Prophylaxis is particularly important for individuals in whom endocardial infec- tion is associated with high morbidity and mortality.
REFERENCES
1. Dajani AS, Taubert KA, Wilson W, et al. Prevention of bacterial endocarditis.
Recommendations by the American Heart Association. JAMA 277:1794–
1801, 1997.
2. Horstkotte D, Follath F, Gutschik E, et al. Guidelines on prevention, diagnosis and treatment of infective endocarditis executive summary; the task force on infective endocarditis of the European society of cardiology. Eur Heart J 25:
267–276, 2004.
3. Steckelberg JM, Wilson WR. Risk factors for infective endocarditis. Infect Dis Clin North Am 7:9–19, 1993.
