Match each clinical presentation of infective endocarditis with the most likely causative microorganism.
- An individual with active injection drug use presenting with high fever, tricuspid valve vegetations, and scattered cavitary pulmonary infiltrates.Staphylococcus aureus
- An older adult who develops subacute infective endocarditis shortly after undergoing cystoscopy and transurethral prostatectomy.Enterococcus faecalis
- A patient diagnosed with native valve endocarditis who is concurrently found to have an asymptomatic ascending colon adenocarcinoma.Streptococcus gallolyticus (S. bovis)
- A patient hospitalized for high-grade bacteremia and paravalvular regurgitation noted four weeks following mechanical prosthetic valve implantation.Staphylococcus epidermidis
- A previously healthy individual with a known structural heart defect who develops slowly progressive fatigue and splinter hemorrhages following extensive dental work.Viridans group streptococci
Answer
The presentations map to established clinical risk factors: injection drug use links to Staphylococcus aureus, genitourinary procedures to Enterococcus faecalis, colon cancer to Streptococcus gallolyticus, early prosthetic valves to Staphylococcus epidermidis, and dental procedures to Viridans group streptococci.
Each matching pair relies on classic pathophysiologic associations. Staphylococcus aureus dominates in intravenous drug users due to skin flora introduction into venous circulation. Enterococcus faecalis is linked to genitourinary tract instrumentation. Streptococcus gallolyticus has a strong association with colorectal malignancy. Staphylococcus epidermidis relies on its biofilm-producing capabilities to infect foreign hardware like recently placed mechanical valves. Finally, Viridans group streptococci reside in the oral cavity and enter the bloodstream during dental procedures to infect structurally abnormal native valves.
Step-by-Step Solution
Key Concept
Risk-factor associations for causative organisms in infective endocarditis.