Chapter 67: Infective Endocarditis
Which of the following statements about infective endocarditis (IE) is correct?
A. In developed countries, rheumatic heart disease is the most frequent predisposing cardiac condition for IE
B. The median age of patients with IE has gradually decreased since the preantibiotic era
C. Antibiotics are sufficient treatment for catheter-related bloodstream infections
D. The majority of IE cases in injection drug users involve the right heart
E. Antibiotic prophylaxis before cardiovascular device implantation does not prevent infectious complications
The answer is D. (Hurst’s The Heart, 14th Edition, Chap. 67) Infective endocarditis (IE) is a disease caused by a microbial infection involving the endothelial lining of intracardiac structures such as the heart valves. In developing countries, rheumatic heart disease remains the most frequent predisposing cardiac condition (option A). However, the epidemiologic features of IE in developed countries have changed considerably in recent decades. The aging of the population has been paralleled by increases in the prevalence of degenerative heart valve disease and in the use of prosthetic heart valves and other intracardiac devices. The median age of patients with IE has gradually increased from 30 to 40 years in the preantibiotic era to 47 to 69 years in the late 20th century (option B). IE is also a dreaded complication of injection (intravenous) drug use. The distinctive feature of IE in intravenous drug users is that it often involves the right heart (option D), with 60% to 70% of cases involving the tricuspid valve. The tricuspid valve may be particularly susceptible to bacterial infection as a result of chronic degenerative changes caused by the repetitive injection of irritants (eg, talcum) into peripheral veins. In the case of catheter-related bloodstream infections, treatment with antibiotics alone yields poor results (option C), and removal of infected catheters or grafts is necessary in most circumstances. A retrospective analysis of patients undergoing pacemaker implantation suggests that antibiotic prophylaxis before device implantation can prevent infectious complications (option E).
The pathogenesis of IE includes all of the following except:
A. Osler nodes and Janeway lesions are systemic manifestations of immunologically induced vasculitis
B. Bacteria adhere to damaged endothelium by binding extracellular matrix components
C. Host endothelial damage is the key predisposing insult
D. Bacterial proliferation creates dense vegetations on sites of injury
E. Infected emboli can result in satellite areas of infection
The answer is A. (Hurst’s The Heart, 14th Edition, Chap. 67) Normal vascular ...