INFECTIVE ENDOCARDITIS   79A

A 55-year-old man who recently emigrated from China presents to the emergency department with a fever. He has had recurring fevers over the past 3 weeks associated with chills, night sweats, and malaise. His medical history is remarkable for “being very sick as a child after a sore throat.” He recently had several teeth extracted for severe dental caries. He is taking no medications. On physical examination, he has a temperature of 38.5°C, blood pressure of 120/80 mm Hg, heart rate of 108 beats/min, respiratory rate of 16 breaths/min, and oxygen saturation of 97% on room air. Skin examination is remarkable for painful nodules on the pads of several fingers and toes. He has multiple splinter hemorrhages in the nail beds and painless hemorrhagic macules on the palms of the hands. Ophthalmoscopic examination is remarkable for retinal hemorrhages. Chest examination is clear. Cardiac examination reveals a grade 3 of 6 holosystolic murmur heard loudest at the left lower sternal border, with radiation to the axilla.

What are the salient features of this patient’s problem? How do you think through his problem?

Salient features: Constitutional symptoms (fever, chills, night sweats, malaise); likely prior rheumatic fever; poor dentition; tachycardia; painful Osler nodes, splinter hemorrhages, painless Janeway lesions; Roth spots on ophthalmoscopy; cardiac murmur

How to think through: Mortality from infective endocarditis (IE) is high, depending on the valve affected and organism. Often, only nonspecific symptoms and signs are apparent at presentation, but delay in diagnosis can be catastrophic. On presentation, this patient had the cardinal constitutional symptoms of fever, chills, night sweats, and malaise. What historical risk factors raise the likelihood of IE? (History of rheumatic fever, prosthetic valve, injection drug use.) What signs are associated with IE? (Fever, murmur, embolic lesions, peripheral stigmata.) What else should you look for in your initial evaluation? (Altered mental status, inflammatory arthritis, hematuria, embolic infarctions on chest radiograph.) What are the key tests for diagnosis and treatment? (Blood cultures and echocardiogram.) What are the most common organisms in IE? (Viridians strains of streptococci, Staphylococcus aureus, enterococci, coagulase-negative staphylococci.)

INFECTIVE ENDOCARDITIS   79B

What are essentials of diagnosis and general considerations regarding infective endocarditis?

Essentials of Diagnosis

Risk factors: preexisting organic heart lesion, prosthetic valve, injection drug use

Fever, new or changing heart murmur, evidence of systemic emboli, positive blood culture findings

Evidence of vegetation on echocardiography

General Considerations

Clinical presentation is dictated by the infecting organism, valve infected, and route of infection.

More virulent organisms, particularly S. aureus, cause rapidly progressive infections with acute valvular regurgitation and myocardial abscess.

Subacute presentation is more common from viridians strains of streptococci and enterococci, but it can also be from other gram-positive and gram-negative bacilli, yeasts, and fungi.

The initiating event is infection of the valve during bacteremia.

Native valve endocarditis is most commonly caused by S. aureus (∼40%), viridans streptococci (∼30%), and enterococci (5%–10%).

Prosthetic valve endocarditis early after implantation is more likely to be caused by gram-negative organisms, fungi, and both coagulase-positive and coagulase-negative staphylococci.

Injection drug users are more likely to have S. aureus and tricuspid valve infection.

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