Chapter 33 Endocarditis
1 What are the important clinical manifestations of endocarditis?
Several processes contribute to the clinical signs and symptoms of infective endocarditis, including valvular involvement with intracardiac complications, high-grade and persistent bacteremia (which may lead to metastatic foci), bland or septic embolization to any organ, and immune complex formation. Fever occurs in 80% of patients, and nonspecific symptoms, including anorexia, weight loss, malaise, fatigue, chills, weakness, nausea, vomiting, and night sweats, are very common. Although heart murmurs are common, the so-called changing murmur is relatively uncommon.
The incidence of peripheral manifestations has decreased. Osler nodes, although not specific for endocarditis, may occur in 10% to 25% of all cases and are generally seen in subacute cases. Janeway lesions (i.e., macular, painless plaques on the palms and soles) are seen in fewer than 10% of cases. Clubbing may be seen if the disease is long-standing and may occur 10% to 20% of the time. Splenomegaly occurs in 25% to 60% of cases, generally those with subacute disease. Joint complaints may occur in approximately 40% of patients and may be relatively innocuous with low back pain or myalgias and arthralgias. Musculoskeletal symptoms may also be quite severe, including frank septic arthritis and severe low back pain. Other less common musculoskeletal manifestations include septic bursitis, sacroiliitis, septic diskitis, and polymyalgia rheumatica. Long-standing subacute endocarditis may present as chronic wasting syndrome mimicking cancer or human immunodeficiency virus infection. Signs and symptoms of embolic episodes are determined by the location of the embolism. Patients with splenic emboli may have left upper quadrant pain, left-sided pleural effusions, or a rub. Renal infarction from a septic embolus may present as flank pain and hematuria. Immune complex formation may lead to renal insufficiency. Cough and shortness of breath with chest pain often accompany pulmonary emboli. Coronary emboli occur rarely and may present with myocarditis, arrhythmias, myocardial infarction, or a combination thereof. Extension into the pericardial space may lead to purulent pericarditis with severe chest pain and hemodynamic compromise. Unexplained heart failure in a young patient without prior cardiac disease should prompt an investigation for infectious endocarditis.
2 Are there differences in the manifestations of endocarditis in elderly patients?
There does appear to be an increased incidence of endocarditis in elderly patients that may be related to an increased life span in patients with rheumatic and other cardiovascular diseases, with a commensurate increase among patients with calcific and degenerative heart disease. In addition, the increase in prolonged catheter use, implantable devices, and dialysis catheters increases the incidence of nosocomial endocarditis. Endocarditis in elderly persons is more likely to occur in men, with a ratio of approximately 2 to 8:1 in patients older than 60 years of age. Staphylococci and streptococci account for approximately 80% of the cases in elderly persons, and Streptococcus bovis may be noted more frequently in elderly patients associated with underlying colonic malignancy. The clinical presentation of endocarditis may be nonspecific, including lethargy, fatigue, malaise, anorexia, failure to thrive, and weight loss (which may be attributed to aging or other medical illnesses common in the elderly). In addition, fever, which occurs in roughly 80% of patients with endocarditis, is more likely to be absent in elderly patients. Worsening heart failure and murmurs may be attributed to underlying disease and therefore erroneously neglected. Consequently, a high index of suspicion is necessary.
3 What are the Duke criteria for the diagnosis of endocarditis? How have they been modified?
The original Duke criteria for the diagnosis of infective endocarditis stratified patients into three categories:
Definite: identified by using clinical or pathologic criteria (Box 33-1)
Rejected: firm alternative diagnosis for manifestations of endocarditis or resolution of manifestations of endocarditis, with antibiotic therapy for 4 days or less, or no pathologic evidence of infective endocarditis at surgery or autopsy, after antibiotic therapy for 4 days or less
Box 33-1 Original duke pathologic and clinical criteria for diagnosis of endocarditis
Pathologic Criteria
Pathologic criteria include microorganisms demonstrated by culture or histology in a vegetation or in a vegetation that has embolized or in an intracardiac abscess or pathologic lesions, including vegetation or intracardiac abscess, confirmed by histologic analysis showing active endocarditis.
Clinical Criteria
Clinical criteria include either two major criteria or one major and three minor criteria or five minor criteria from the following list:
Major criteria are the following:
Positive blood culture results with a typical microorganism for infective endocarditis from two separate blood cultures (viridans streptococci, including nutritionally variant strains; S. bovis, HACEK group, or community-acquired S. aureus or enterococci in absence of a primary focus)
Persistently positive blood culture result, defined as recovery of a microorganism consistent with infective endocarditis from blood cultures drawn more than 12 hours apart or all of three or a majority of four or more separated blood cultures with first and last drawn at least 1 hour apart
Echocardiogram result positive for infective endocarditis, including one of the following:
Oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation
Minor criteria are the following:
Predisposition: predisposing heart condition or IV drug use
Fever: body temperature > 38° C (100.4° F)
Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, conjunctival hemorrhages, Janeway lesions
Immunologic phenomena: glomerulonephritis, Osler nodes, Roth spots, rheumatoid factor
Microbiologic evidence: positive blood culture result but not meeting major criterion as noted previously or serologic evidence of active infection with organism consistent with infective endocarditis
Echocardiogram: consistent with infective endocarditis but not meeting major criterion as noted previously
Since the original Duke criteria were published in 1994, several refinements have been made based on studies evaluating the sensitivity and specificity of the criteria:
Bacteremia with Staphylococcus aureus was included as a major criterion only if it was community acquired. Subsequent research has shown that a significant proportion of patients with nosocomially acquired staphylococcal bacteremia will have documented infective endocarditis. Consequently, S. aureus bacteremia is now included as a major criterion regardless of whether the infection is nosocomial or community acquired.
An additional major criterion was added as follows: single blood culture result positive for Coxiella burnetii or anti–phase 1 immunoglobulin G antibody titer > 1:800.
An additional statement was added to the major criteria regarding endocardial involvement and an echocardiogram positive for infective endocarditis. The statement now includes the following: Transesophageal echocardiography (TEE) is recommended for patients with prosthetic valves, diagnoses rated at least “possible infective endocarditis” by clinical criteria, or complicated infective endocarditis (paravalvular abscess); transthoracic echocardiography (TTE) should be the first test in other patients.
The echocardiogram minor criterion was eliminated.
The category of “possible endocarditis” was adjusted to include the following criteria: one major and one minor criterion or three minor criteria. This so-called floor was designated to reduce the proportion of patients assigned to the “possible” category.
4 What are the organisms that most often cause endocarditis?
The etiologic agents of infective endocarditis include the following:
Viridans streptococci: 30%-40%
Coagulase-positive organisms: 10%-27%
Coagulase-negative organisms: 1%-3%
Gram-negative aerobic bacilli: 1%-13%
S. aureus tends to be the most common etiologic agent of infective endocarditis in intravenous (IV) drug users. Pseudomonas aeruginosa is also more commonly seen in patients using IV drugs. In patients with prosthetic valves, the microbiology is somewhat dependent on whether they have early (< 2 months after valve replacement) versus late (> 12 months) endocarditis. Staphylococci account for 40% to 60% of the cases of early onset prosthetic valve endocarditis. Coagulase-negative staphylococci account for approximately 30% to 35% of cases, and S. aureus accounts for approximately 20% to 25%. Patients who have late-onset prosthetic valve endocarditis are more likely to have the organisms most commonly seen in patients with native valve endocarditis, with one exception: coagulase-negative staphylococci are seen more frequently (approximately 10%-12%) in patients with prosthetic valves. Patients who have fungal endocarditis are often IV drug users, have recently undergone cardiovascular surgery, or have received prolonged IV antibiotic therapy.
5 What are the HACEK organisms? How often do they cause endocarditis?
HACEK is an acronym for a group of fastidious, slow-growing, gram-negative bacteria:
H:Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus paraphrophilus, Haemophilus influenzae
A:Actinobacillus actinomycetemcomitans
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