A patient with colorectal cancer develops septicemia complicated by endocarditis. You would expect the blood
cultures to grow
A. Streptococcus agalactiae
B. Streptococcus bovis
C. Streptococcus pneumoniae
D. Streptococcus pyogenes
E. Streptococcus viridans
The correct answer is B.Streptococcus bovis is a Group D streptococcus. There is a significant association
between S. bovis bacteremia and endocarditis with carcinoma of the colon and other colonic diseases. Every
patient with S. bovis bacteremia should undergo gastrointestinal and cardiac evaluation. Up to 50% of patients
with S. bovis bacteremia are reported to have underlying colonic malignancies. In another study, 25-50% of
cases of S. bovis bacteremia were associated with endocarditis, especially in patients with preexisting valvular
Streptococcus agalactiae(choice A) is an important cause of maternal and neonatal bacteremia and neonatal
meningitis. It is part of the normal flora of the gastrointestinal tract and the female genital tract.
Streptococcus pneumoniae(choice C) is a leading cause of community-acquired pneumonia, meningitis in
adults, otitis media (especially in children), and sinusitis. Spontaneous peritonitis due to S. pneumoniae is
reported in children with ascites from nephrotic syndrome. Asplenia predisposes patients to severe infections
with S. pneumoniae and other encapsulated organisms. S. pneumoniae infections are also more frequent and
unusually severe in patients with sickle cell anemia, multiple myeloma, alcoholism, and hypogammaglobulinemia.
S. pneumoniae is now the leading cause of invasive bacterial respiratory disease in patients with AIDS.
Streptococcus pyogenes(choice D) is the most common cause of bacterial pharyngitis. Complications include
paratonsillar abscesses, otitis media, and sinusitis. Long-term sequelae include rheumatic fever and
poststreptococcal glomerulonephritis. S. pyogenes is also responsible for many skin and soft tissue infections.
The organism also produces many toxins that produce a variety of diseases.
Streptococcus viridans(choice E), or the viridans Streptococci, are the most common cause of subacute
bacterial endocarditis, which should be suspected in cases of viridans streptococcal bacteremia. One species of
viridans Streptococci, Streptococcus milleri, is frequently associated with pyogenic abscesses, especially of the
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