Chapter 118. Infective Endocarditis (Part 7)

Experts favor echocardiographic evaluation of all patients with a clinical diagnosis of endocarditis; however, the test should not be used to screen patients with a low probability of endocarditis (e.g., patients with unexplained fever). An American Heart Association approach to the use of echocardiography for evaluation of patients with suspected endocarditis is illustrated in Fig. 118-4. A negative TEE when endocarditis is likely does not exclude the diagnosis but rather warrants repetition of the study in 7–10 days.Figure 118-4Thediagnosticuseoftransesophagealandtranstrachealechocardiography (TEE and TTE, respectively). ...
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Chapter 118. Infective Endocarditis (Part 7) Chapter 118. Infective Endocarditis (Part 7) Experts favor echocardiographic evaluation of all patients with a clinicaldiagnosis of endocarditis; however, the test should not be used to screen patientswith a low probability of endocarditis (e.g., patients with unexplained fever). AnAmerican Heart Association approach to the use of echocardiography forevaluation of patients with suspected endocarditis is illustrated in Fig. 118-4. Anegative TEE when endocarditis is likely does not exclude the diagnosis but ratherwarrants repetition of the study in 7–10 days. Figure 118-4 The diagnostic use of transesophageal and transtrachealechocardiography (TEE and TTE, respectively). † High initial patient risk forendocarditis as listed in Table 118-8 or evidence of intracardiac complications(new regurgitant murmur, new electrocardiographic conduction changes, orcongestive heart failure). *High-risk echocardiographic features include largevegetations, valve insufficiency, paravalvular infection, or ventriculardysfunction. Rx indicates initiation of antibiotic therapy. [Reproduced withpermission from Diagnosis and Management of Infective Endocarditis and ItsComplications (Circulation 1998; 98:2936-2948. © 1998 American HeartAssociation.)] Other Studies Many laboratory studies that are not diagnostic—i.e., complete bloodcount, creatinine determination, liver function tests, chest radiography, andelectrocardiography—are nevertheless important in the management of patientswith endocarditis. The erythrocyte sedimentation rate, C-reactive protein level,and circulating immune complex titer are commonly increased in endocarditis(Table 118-2). Cardiac catheterization is useful primarily to assess coronary arterypatency in older individuals who are to undergo surgery for endocarditis. Infective Endocarditis: Treatment Antimicrobial Therapy It is difficult to eradicate bacteria from the avascular vegetation in infectiveendocarditis because this site is relatively deficient in host defenses and becausethe largely nongrowing, metabolically inactive bacteria are less easily killed byantibiotics. To cure endocarditis, all bacteria in the vegetation must be killed;therefore, therapy must be bactericidal and prolonged. Antibiotics are generallygiven parenterally and must reach high serum concentrations that will, throughpassive diffusion, lead to effective concentrations in the depths of the vegetation.The choice of effective therapy requires precise knowledge of the susceptibility ofthe causative microorganisms. The decision to initiate treatment before a cause isdefined must balance the need to establish a microbiologic diagnosis against thepotential progression of disease or the need for urgent surgery (see BloodCultures, above). The individual vulnerabilities of the patient should be weighedin the selection of therapy—e.g., simultaneous infection at other sites (such asmeningitis), allergies, end-organ dysfunction, interactions with concomitantmedications, and risks of adverse events. Although given for several weeks longer, the regimens recommended forthe treatment of endocarditis involving prosthetic valves (except forstaphylococcal infections) are similar to those used to treat native valve infection(Table 118-4). Recommended doses and durations of therapy should be adhered tounless alterations are required by adverse events. Table 118-4 Antibiotic Treatment for Infective Endocarditis Caused byCommon Organismsa Organism Drug (Dose, Duration) Comments Streptococci Penicillin- Penicillin G (2–3 mU IV —susceptibleb q4h for 4 weeks)streptococci, S. bovisstreptococci, S. bovis Ceftriaxone (2 g/d IV as Can use ceftriaxone a single dose for 4 weeks) in patients with nonimmediate penicillin allergy Vancomycinc (15 mg/kg Use vancomycin in IV q12h for 4 weeks) patients with severe or immediate β-lactam allergy Penicillin G (2–3 mU IV Avoid 2-week q4h) or ceftriaxone (2 g IV qd) regimen when risk of for 2 weeks aminogl ...