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KEY CONCEPTS
Infective endocarditis usually occurs in adult patients with specific risk factors (eg, injection drug use, heart failure, valvular disease, and healthcare exposure) and those with implanted cardiac material (eg, prosthetic heart valves).
Three groups of organisms cause most cases of infective endocarditis: staphylococci, streptococci, and enterococci.
The clinical presentation of infective endocarditis is highly variable and nonspecific, although a fever and murmur are usually present. Classic peripheral manifestations (eg, Osler's nodes) may or may not occur.
The diagnosis of infective endocarditis requires the integration of clinical, laboratory, and echocardiographic findings. The two major diagnostic criteria are bacteremia and echocardiographic changes (eg, valvular vegetation).
Treatment of infective endocarditis involves isolation of the infecting pathogen and determination of antimicrobial susceptibilities, followed by high-dose, parenteral, bactericidal antibiotics for an extended period.
Surgical replacement of the infected heart valve is an important adjunct to endocarditis treatment in certain situations (eg, patients with acute heart failure).
β-lactam antibiotics, such as penicillin G (or ceftriaxone), nafcillin, and ampicillin, remain the drugs of choice for streptococcal, staphylococcal, and enterococcal endocarditis, respectively.
Combination regimens, such as ampicillin plus an aminoglycoside antibiotic, are recommended to achieve a synergistic bactericidal effect in the treatment of enterococcal endocarditis. Adjunctive aminoglycosides also may decrease the emergence of resistant organisms (eg, prosthetic valve endocarditis caused by coagulase-negative staphylococci) and hasten the pace of clinical and microbiologic response (eg, some streptococcal and staphylococcal infections).
Vancomycin is reserved for patients with immediate β-lactam allergies and the treatment of resistant organisms.
Antimicrobial prophylaxis is used to prevent infective endocarditis for patients who are at the highest risk before a bacteremia-causing procedure.
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Patient Care Process for Infective Endocarditis
Collect
Patient characteristics (eg, age, sex, height, weight, pregnancy status, allergies)
Patient history (eg, past medical, surgical, family)
Social history (eg, ethanol/IV drug abuse, recent travel, home residence, exposure to animals) and dietary habits, including intake of unpasteurized dairy products
Current medication use, including prescription, nonprescription, and other substances, with emphasis on previous inpatient and outpatient antimicrobial use
Objective data
Temperature, blood pressure, respiratory rate, complete blood count (eg, white blood cell count, red blood cell count, hemoglobin, platelets), chemistry panel (eg, serum creatinine), urinalysis
Results from blood and/or valve tissue cultures and specialized testing (eg, serology, polymerase chain reaction)
Diagnostic testing (eg, electrocardiograph, chest radiograph, echocardiography)
Assess
Identify risk factors (eg, immunocompromised status, recent dental procedure, central venous catheter, IV drug abuse, dietary habits)
Assess signs and symptoms (eg, temperature >100.4 °F (38 °C), [see Table 129-2], radiographic evidence, pathogen identification, physical examination findings)
Determine potential infectious etiologies based on patient history, current and previous antimicrobial use, risk factors, microbiologic data, and diagnostic testing
Determine the need for surgical intervention (eg, heart failure, persistent bacteremia, persistent vegetation)
Identify patients with underlying high-risk cardiac complications that would be candidates for antimicrobial prophylaxis
Plan*
Determine the most appropriate empirical antimicrobial therapy, including dose, route, and frequency, based ...