Native-valve infective endocarditis caused by Enterobacteriaceae: report on 9 cases and literature review.

Although the demographic characteristics of patients who develop infective endocarditis (IE) have changed over the last few decades, Enterobacteriaceae remain rarely responsible. We report the clinical and epidemiological characteristics of 9 patients with native-valve Enterobacteriaceae IE from 6 French medical intensive care units over a 10-y period and have identified 29 additional cases in the literature. Nearly a third of the 38 patients were immunocompromised and/or had previously known valvular heart disease. Salmonella spp. and Yersinia spp. were the most frequently isolated microorganisms reported in the literature. The overall mortality rate was 24% (9/38) and was lower for operated patients (10% (1/10)) compared to those who did not undergo valve surgery (31% (8/26)). Our results confirmed the rarity of native-valve endocarditis caused by Enterobacteriaceae, pathogens frequently responsible for nosocomial and community-acquired bacteraemias. This paradox may be explained by susceptibility to the bactericidal action of serum and the inability of these bacteria to colonize the endocardium.