The patient is likely presenting with subacute bacterial endocarditis (SBE) suggested by his malaise, fever/chills, new systolic murmur, hand lesions (Osler nodes), and history of mitral valve repair (people with valvular lesions are more susceptible to BE). Given his recent cystoscopy in the setting of recurrent UTIs, the most likely source of his bacteremia and, ultimately, SBE, is his urinary tract, making enterococci the most likely organism.
SBE differs from acute BE in that the onset of symptoms is more gradual and the symptoms are less severe. The most common pathogens for SBE are the Viridans group streptococci, enterococci, and coagulase negative staphylococci (e.g. staph epidermis). The most common pathogens for acute BE are Staphylococcus aureus, Neisseria gonorrhoeae, Streptococcus pneumoniae, and Streptococcus pyogenes.
As Giessel et al. note, enterococci is becoming increasingly resistant to many antibiotics, making medical treatment challenging.
The American Heart Association's (AHA) updated guidelines on the prevention of infective endocarditis recommend that for patients at risk for IE (see illustration A) who are undergoing a cystoscopy and have an enterococcal UTI, antibiotics may be given.
Image A shows Osler nodes associated with BE.
Illustration A is a table from the AHA delineating cardiac conditions for which BE prophylaxis is reasonable.
Answers 1 & 5: Staphyloccocus aureus and Neiserria gonorrhoeae generally produce acute, not subacute, BE.
Answer 2: The source of bacteremia/BE caused by Staphylococcus epidermis is usually the skin.
Answer 3: The source of bacteremia/BE caused by Viridans streptococci is usually the upper respiratory tract.
Giessel BE, Koenig CJ, Blake RL Jr. Management of bacterial endocarditis. Am Fam Physician. 2000 Mar 15;61(6):1725-32, 1739.
PMID:10750879 (Link to Abstract)
Wilson W, Taubert KA, Gewitz M, Lockhart PB, Baddour LM, Levison M, Bolger A, Cabell CH, Takahashi M, Baltimore RS, Newburger JW, Strom BL, Tani LY, Gerber M, Bonow RO, Pallasch T, Shulman ST, Rowley AH, Burns JC, Ferrieri P, Gardner T, Goff D, Durack DT. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young,
PMID:17446442 (Link to Abstract)