Page 864 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 67: Endocarditis and Other Intravascular Infections 595

Routine laboratory findings are neither specific nor sensitive, therefore and left ventricular dysfunction. Therefore, when IE is likely clinically,
15
they are of little help in making or excluding a diagnosis of IE. Urinalysis a TEE should be obtained to assist in diagnosis and management. 16,17
reveals proteinuria or hematuria in roughly 50% of patients. Anemia and Heidenreich et al suggested that if the pretest probability of IE is between
thrombocytopenia are present in 80% and 20%, respectively. A leukocy- 4% and 60%, it is cost effective to proceed to TEE without TTE. 18
tosis is present in only 30% and rheumatoid factor may be positive in ■
patients with a subacute presentation. MANAGEMENT
■ DIAGNOSIS Critically ill ICU patients should have empiric antibiotics begun immedi-

A definitive clinical diagnosis is made when two major, one major and ately after blood cultures have been obtained. It is important to use bacte-
riocidal agents dosed at appropriate intervals to maintain therapeutic levels
three minor, or five minor criteria are met as defined by the modified at all times. An empiric agent with activity against MRSA is necessary given
Duke Criteria. The first major criterion is two positive blood cultures the prevalence of community-acquired MRSA infection. Vancomycin
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for organisms, which typically cause IE. The second major criterion is remains the gold standard, but newer agents include daptomycin, linezolid,
echocardiogram findings typical of IE; these findings include an oscil- tigecycline, and ceftaroline; daptomycin is currently the only new agent
lating intracardiac mass on the valve or supporting structures in the FDA approved to treat bacteremia and right-sided endocarditis. 19
path of regurgitant jets, an abscess, or new valvular regurgitation. Minor Empiric regimens also need to be active against enterococci and
criteria include gram-negative bacilli. Standard therapy is to add an aminoglycoside to
vancomycin. This regimen is adjusted when the blood culture results
• Predisposing valvular disease are known (Table 67-2). If Pseudomonas is cultured, then treatment is
• Intravenous drug use usually adjusted to an antipseudomonal penicillin or cephalosporin plus
• Fever an aminoglycoside, though some data suggest that two agents may not
• Vascular phenomena be necessary. 20
The most critical management decision to make early in the course
• Immunologic phenomena of a patient with IE other than antibiotic therapy is whether or not
• Culture or serologic evidence of infection that does not meet major surgical intervention is indicated. Early valve replacement is generally
criteria indicated when a patient has refractory congestive heart failure despite
21
A pathologic diagnosis is made when pathologic lesions are identified medical management. In this setting, early surgery is associated with
and microorganisms are demonstrated on histologic examination of a an improved survival. Other indications for valve replacement include
cardiac vegetation, a vegetation that has embolized or from an intracar- • Persistent fever or bacteremia despite appropriate therapy
diac abscess. • Highly resistant microorganisms, that is, Candida, Pseudomonas,
A diagnosis of possible, but not definite, endocarditis is made when Coxiella
there is one major and one minor criterion or three minor criteria.
Blood cultures are the most important laboratory tests in making a • Development of an abscess or fistula
diagnosis of IE. Blood cultures are positive in 90% to 95% of patients • Large (>1 cm), oscillating vegetation
who have not received prior antimicrobial therapy. In 5% to 10% of • Prosthetic valve dehiscence
patients, no etiologic organism is isolated using routine blood culture
methods. Bacterial causes of culture-negative endocarditis in patients Kim et al have shown that early surgery is also associated with a lower
22,23
who have not received prior antibiotics include infection with morbidity and mortality due to fewer embolic events.
Treatment consists of intravenous antibiotics given for 4 to 8 weeks
• Anaerobes depending on the organism and whether or not the patient has native
• Nutritionally deficient streptococci valve versus prosthetic valve infection. However, a 2-week course of
• Coxiella burnetii treatment may be given in patients with uncomplicated NVE due to
highly penicillin-sensitive viridans streptococcal or in patients with
• Legionella pneumophila uncomplicated right-sided infection due to S aureus. 24,25
• Chlamydia psittaci Standardization of care regarding antimicrobial therapy and surgical
• C pneumoniae indications has been shown to be associated with a lower 1-year mortality. 26
• Members of the HACEK group ■ PROGNOSIS
HACEK is an acronym for a group of small, fastidious, gram-negative The prognosis of IE is determined by the specific infecting organism,
bacilli that includes Haemophilus spp, Actinobacillus actinomycetem- the valve that is involved, and the presence of certain complications.
comitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella S aureus typically produces significant tissue destruction so is fatal in
kingae. It is important to ask the microbiology laboratory to keep blood more than a third of patients when there is mitral or aortic valve involve-
14
cultures for 3 weeks rather than the standard 1 week when attempting ment. MRSA has been associated with an even higher mortality as com-
to identify these organisms. pared to methicillin-sensitive S aureus infections. Patients admitted
27
Many patients in the ICU undergo a transthoracic echocardiogram to the ICU have a mortality of 45% to 56%. The prognosis is better in
3
(TTE) to assess left ventricular function in order to evaluate unexplained patients who acquire right-sided IE through intravenous drug use.
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hypotension or pulmonary edema as well as to evaluate a patient with Data show that left-sided vegetations greater than 1 cm in diameter are
a new diagnosis of congestive heart failure. Also, a TTE is often done associated with a higher rate of adverse complications. Also associated
29
when a patient in the ICU has a positive blood culture. However, this with a higher mortality are
should only be done in a patient with low suspicion of IE or one who is at
low risk for complications. All other patients with suspected IE should • Mitral valve involvement
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undergo a transesophageal echocardiogram (TEE). Echocardiography • Refractory heart failure
should be done as soon as the diagnosis of IE is suspected, preferably • Shock
within 12 hours of the initial evaluation. Colreavy et al demonstrated • Major embolic events
that TEE performed by intensive care physicians is useful not only in
making a diagnosis of IE, but also in managing critically ill patients • Intracardiac abscesses
with unexplained hypotension, pulmonary emboli, pulmonary edema, • Major organ system failure

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