Fatal endocarditis due to Aerococcus urinae

Aerococcus species are Gram-positive cocci having Gram-stain characteristics of staphylococci (i.e., form clusters), but biochemical and growth characteristics resembling streptococci and enterococci (i.e., catalase-negative, alpha-hemolytic growth on blood agar). A case of fatal endocarditis due to Aerococcus urinae is presented. Endocarditis should be suspected and, if confirmed, treated aggressively when A. urinae is recovered from blood cultures.