Anatomic Pathology: Cardiac Pathology

• This question requires you to recognize the pathophysiology of the patient’s death and to understand the difference between cause of death and mechanism of death.

• The mechanism of death was bacterial endocarditis, but the cause of death was intravenous drug abuse, which caused the patient to become infected with hepatitis C virus, which led to cirrhosis, which caused varices, which bled leading to admission to the hospital where he acquired endocarditis.

• Staphylococcus aureus is the most common cause of both hospital-acquired and community-acquired endocarditis. Coagulase-negative Staphylococcus is also a common cause of hospital-acquired endocarditis. Enterococcus species are the next most common cause of hospital-acquired endocarditis. In community-acquired endocarditis, viridans streptococci are the second most common cause.

• This patient had several risk factors for infective endocarditis, including recent hospital admission and intravenous drug use. Endocarditis is considered to be hospital acquired if it begins within 3 days of admission or within 60 days if the patient had a risk factor for bacteremia.

• The fact that this patient had mitral valve endocarditis supports the supposition that it is hospital acquired because intravenous drug use more frequently causes right-sided disease.

• The HACEK organisms are Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae.