A 67-year-old man comes to the emergency department with low-grade fevers and fatigue. He has no history of heart disease. His temperature is 38.4 C (101.1 F), blood pressure is 117/76 mm Hg, pulse is 82/min, and respirations are 14/min. On examination, there is a diastolic murmur at the left sternal border. He has nontender erythematous macules on his hands and feet. Blood cultures show gram-positive cocci that are catalase-negative and able to grow in hypertonic (6.5%) saline and bile. This patient's medical history is most likely to include which of the following procedures within the past month?

Question

A 67-year-old man comes to the emergency department with low-grade fevers and fatigue.  He has no history of heart disease.  His temperature is 38.4 C (101.1 F), blood pressure is 117/76 mm Hg, pulse is 82/min, and respirations are 14/min.  On examination, there is a diastolic murmur at the left sternal border.  He has nontender erythematous macules on his hands and feet.  Blood cultures show gram-positive cocci that are catalase-negative and able to grow in hypertonic (6.5%) saline and bile.  This patient's medical history is most likely to include which of the following procedures within the past month?

Quizplus · Accepted Answer

11ec160b_3824_3123_9249_fb052ce4aa65_MD0001_00 Enterococcal endocarditis (representing up to 30% of nosocomial endocarditis cases) usually occurs in elderly men who have recently undergone manipulation of areas colonized by this organism. The genitourinary tract (eg, cystoscopy) is the most common portal of entry; gastrointestinal (eg, colonoscopy) or obstetric procedures are also risk factors. Enterococci can also cause urinary tract infections (most common), intraabdominal and pelvic infections, and wound infections. Enterococci are typically gamma-hemolytic (no hemolysis on agar), catalase-negative, pyrrolidonyl arylamidase-positive, Lancefield Group D gram-positive cocci that can grow in hypertonic (6.5%) saline and bile. The most common species of enterococci (formerly classified under the genus Streptococcus) are Enterococcus faecalis (80%-90%) and Enterococcus faecium (10%-15%). Enterococci are resistant to many antibiotics and can be very difficult to treat. A cell wall-active agent (such as ampicillin) is often combined with an aminoglycoside for synergistic effect, but increasingly bacteria resistant to both aminoglycosides and β-lactams (including penicillinase-resistant types) are emerging. Strains with vancomycin or linezolid resistance have also appeared. (Choice B) Dental extraction is associated with endocarditis caused by viridans group streptococci (VGS). In most cases, VGS cause subacute bacterial endocarditis in already abnormal heart valves (eg, congenital valvular abnormalities, valves damaged by rheumatic fever). VGS do not grow on hypertonic saline. In addition, almost all VGS species do not grow on bile (VGS are also considered bile-insoluble as they exhibit no cell lysis in the presence of bile, in contrast to the bile-soluble S pneumoniae). (Choice C) Removal of a nasal polyp can cause transient bacteremia. Organisms that colonize the nose include Corynebacterium species, Haemophilus species, staphylococci, streptococci, and Neisseria species. Of these, staphylococci and streptococci may cause endocarditis, but the organism described displays characteristics of Enterococcus. (Choice D) Sinus infections are usually caused by S pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis. S pneumoniae would be a very rare cause of endocarditis and is usually identified by being bile-soluble and optochin-sensitive. (Choice E) Skin biopsy is a benign procedure that would be unlikely to cause endocarditis. Skin is colonized with many bacteria, including Staphylococcus and Streptococcus species, Corynebacterium species, and Bacillus species. Educational objective: Enterococcus is a component of the normal colonic and urogenital flora and is capable of growing in hypertonic saline and bile. It is gamma-hemolytic, catalase-negative, and pyrrolidonyl arylamidase-positive. Genitourinary instrumentation or catheterization has been associated with enterococcal endocarditis. __________ References: Enterococcal endocarditis on native and prosthetic valves: A review of clinical and prognostic factors with emphasis on hospital-acquired infections as a major determinant of outcome. (http://www.ncbi.nlm.nih.gov/pubmed/18004181) It's not easy being green: The viridans group streptococci, with a focus on pediatric clinical manifestations. (http://www.ncbi.nlm.nih.gov/pubmed/20810781)

A 67-Year-Old Man Comes to the Emergency Department with Low-Grade