Prosthetic valve endocarditis due to small-colony staphylococcal variants.

Although Staphylococcus epidermidis is a major cause of prosthetic valve endocarditis, little is known about the pathogenesis of this disease. In one case described herein, small-colony variant forms of S. epidermidis were isolated from clinical specimens obtained from a patient with prosthetic valve endocarditis. Data from the rat model of experimental endocarditis provide further evidence that small-colony variants may be operative in the production of prosthetic valve infection. Moreover, a review of the literature indicates that small-colony variants could account for the subtle clinical course after prolonged dormant infection that characterizes S. epidermidis prosthetic valve endocarditis. It is therefore hypothesized that small-colony variants of S. epidermidis may play a role in the pathogenesis of prosthetic valve endocarditis.