Coagulase-negative staphylococcal endocarditis. Occurrence in patients with mitral valve prolapse.

Although coagulase-negative staphylococci (CoNS) are frequent etiologic agents in prosthetic valve endocarditis, they rarely infect native heart valves. We report three cases of CoNS endocarditis in patients with mitral valve prolapse (MVP). Review of other reports of MVP-associated endocarditis and of the limited experience with CoNS infection of native heart valves suggests that our experience is not unique. Coagulase-negative staphylococcal endocarditis superimposed on MVP may be difficult to recognize and to treat. The cardiac dysfunction can be quite subtle, the clinical course indolent, the blood culture results difficult to interpret, and the response to antimicrobial agents suboptimal.