Final answer:
Enterococcus species, particularly Enterococcus faecalis, are the most common pathogens in endocarditis after a GI or GU exam. They can enter the bloodstream through breaches during medical procedures and require treatment with high doses of intravenous antibiotics.
Step-by-step explanation:
The most common pathogen in endocarditis following a recent gastrointestinal (GI) or genitourinary (GU) examination is likely Enterococcus species, particularly Enterococcus faecalis. These bacteria are common inhabitants of the human gastrointestinal tract and can be opportunistic pathogens. They are well-known for causing urinary tract infections and endocarditis, especially after procedures that involve the GI or GU tracts. Diagnosis of infective endocarditis involves blood cultures, an echocardiogram, and assessment of clinical symptoms. Treatment typically requires high doses of intravenous antibiotics, which are determined by antimicrobial susceptibility testing. Enterococcus faecalis can enter the bloodstream through procedures that accidentally breach normal barrier defenses and can thrive even in patients who may have preexisting heart conditions or prosthetic valves.