Which organism is part of normal colonic flora and can cause UTI and endocarditis, is bile resistant, and may be vancomycin-resistant (VRE)?

• A. Streptococcus pneumoniae
• B. Enterococcus faecalis
• C. Staphylococcus aureus
• D. Streptococcus agalactiae

Answer: (B)

Enterococcus species are residents of the human gut and are well known for causing hospital-associated infections such as urinary tract infections and endocarditis. They are hardy, able to grow in bile and in high-salt conditions, which helps them persist in the intestinal tract and in bile-containing environments. Enterococcus faecalis specifically is a common gut inhabitant that can lead to UTI and endocarditis, and it can acquire resistance to vancomycin, producing vancomycin-resistant Enterococcus (VRE). This combination of being a normal colonic inhabitant, capable of causing these infections, bile tolerance, and potential vancomycin resistance fits the description best. Other organisms listed do not share this exact set of features.