In an elderly man who recently underwent urinary catheterization for prostatic obstruction and now has fever and a diastolic murmur, which organism is most commonly associated with endocarditis after genitourinary procedures?

• A. Pseudomonas aeruginosa
• B. Streptococcus viridans
• C. Enterococcus faecalis
• D. Staphylococcus aureus

Answer: (C)

Genitourinary instrumentation can introduce bacteria from the patient’s own genitourinary and gastrointestinal flora into the bloodstream, and Enterococcus faecalis is the organism most commonly linked to endocarditis after such procedures. In an elderly patient with fever and a diastolic murmur, which points to possible aortic valve involvement, this organism fits the scenario well because enterococci are adept at causing native-valve endocarditis following GU manipulation. Enterococcus faecalis is a gram-positive coccus that resides in the GI/GU tract and is well known for causing infections after genitourinary instrumentation. Other organisms listed aren’t as strongly associated with endocarditis after genitourinary procedures: Streptococcus viridans comes from the oral cavity and dental work, Pseudomonas is common in certain nosocomial UTIs but not the classic post-GU endocarditis agent, and Staphylococcus aureus is a frequent cause of acute endocarditis in other contexts but not the archetypal post-GU procedure offender.