A 44-year-old man comes to the office due to 3 weeks of fever, anorexia, and muscle aches. He has had no cough or shortness of breath. The patient has a 15-pack-year smoking history. Temperature is 38.9 C (102 F), blood pressure is 120/76 mm Hg, pulse is 90/min, and respirations are 16/min. Lungs are clear to auscultation. Cardiac examination reveals a 2/6 holosystolic murmur at the apex. The rest of the physical examination is normal. Both blood cultures grow Streptococcus gallolyticus (formerly Streptococcus bovis biotype I). Echocardiography reveals a small vegetation on the mitral valve with moderate mitral regurgitation. Antibiotics are administered, and 3 days later the patient's fever and systemic symptoms resolve. Which of the following is the best next step in management?

Question

A 44-year-old man comes to the office due to 3 weeks of fever, anorexia, and muscle aches.  He has had no cough or shortness of breath.  The patient has a 15-pack-year smoking history.  Temperature is 38.9 C (102 F), blood pressure is 120/76 mm Hg, pulse is 90/min, and respirations are 16/min.  Lungs are clear to auscultation.  Cardiac examination reveals a 2/6 holosystolic murmur at the apex.  The rest of the physical examination is normal.  Both blood cultures grow Streptococcus gallolyticus (formerly Streptococcus bovis biotype I).  Echocardiography reveals a small vegetation on the mitral valve with moderate mitral regurgitation.  Antibiotics are administered, and 3 days later the patient's fever and systemic symptoms resolve.  Which of the following is the best next step in management?

Quizplus · Accepted Answer

This patient with subacute constitutional symptoms, fever, and a mitral valve vegetation has Streptococcus gallolyticus infective endocarditis (IE). S gallolyticus (formerly Streptococcus bovis biotype I) is 1 of the 4 major species that belong to group D Streptococcus (also known as S bovis/Streptococcus equinus complex). Approximately 60% of patients with S gallolyticus IE have colorectal cancer; this correlation may stem from bacterial adhesion molecules that bind to overexpressed surface ligands on the cancer, which allows it to aggregate and subsequently enter the bloodstream. However, other colorectal pathologies (eg, inflammatory bowel disease) also increase the risk of S gallolyticus IE. Because S gallolyticus infections are tightly linked to colorectal pathology, patients should undergo colonoscopy to evaluate for occult malignancy. Liver function tests and hepatitis serology are also usually warranted because damage to the hepatic sinusoids can increase the risk of infection. (Choice B) Cardiac surgery is generally indicated for patients with IE who have acute heart failure from valvular damage or a large vegetation; mild valve insufficiency and a small vegetation would not generally be indications for surgery. (Choice C) Abdominal CT scan is not as sensitive as colonoscopy for colorectal malignancy and would not be indicated at this time. However, if colonoscopy is negative and liver investigation reveals abnormalities, abdominal CT scan might be required. (Choice D) Patients age ≥50 with a ≥20-pack-year smoking history should undergo low-dose CT scan of the chest to screen for lung cancer. This patient does not meet these criteria; in addition, S gallolyticus IE is not associated with lung malignancy. (Choice E) CT scan of the head can be used to identify masses or hemorrhage. This patient has no symptoms that localize to the brain, and S gallolyticus is not associated with brain pathology. (Choice F) Although guidelines indicate that screening colonoscopy should begin at age 45 or 50 in patients with an average risk of colorectal cancer, the presence of S gallolyticus IE makes this cancer likely; therefore, colonoscopy should be performed now. Performing no additional evaluation would reduce the chance of detecting the cancer at an early stage. Educational objective: Streptococcus gallolyticus (formerly Streptococcus bovis biotype I) bacteremia and infective endocarditis most often occur in patients with underlying colorectal cancer. Patients who develop infection with this pathogen usually require colonoscopy to evaluate for occult malignancy. References: Clinical importance of Streptococcus gallolyticus infection among colorectal cancer patients: systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/21960713)

A 44-Year-Old Man Comes to the Office Due to 3