[Enterococcal endocarditis: a multicenter study of 76 cases]

Abstract

Background: Although enterococci occupy the third position among microorganisms producing infectious endocarditis (IE) following streptococci and Staphylococcus aureus, few multicenter studies have provided an in-depth analysis of enterococcal IE.

Methods: Description of the characteristics of 76 cases of enterococcal left-sided infectious endocarditis (LSIE) (native: 59, prosthetic: 17) retrieved from the database of the Cardiovascular Infections Study Group of the Andalusian Society of Infectious Diseases, with emphasis on the comparison with non-enterococcal LSIE.

Results: Enterococci were the causal agent in 76 of the 696 episodes of LSIE (11%). Compared with non-enterococcal LSIE, enterococcal LSIE was more commonly seen in patients older than 65 (47.4% vs. 27.6%, P<0.0005), and those with chronic diseases (75% vs. 54.6%, P<0.001), calcified valves (18.6% vs. 10%, P<0.05), and previous urinary (30.3% vs. 2.1%, P<0.00001) or abdominal (10.5% vs. 3.1%, P<0.01) infections, and produced a higher rate of relapses (6.6% vs. 2.3%, P<0.05). Enterococcal LSIE was associated with fewer peripheral vascular or skin manifestations (14.5% vs. 27.1%, P<0.05) and fewer immunological phenomena (10.5% vs. 24%, P<0.01). Among the total of patients with enterococcal LSIE, 36.8% underwent valve surgery during hospitalization. In-hospital mortality was 32.9% for enterococcal LSIE, 9.3% for viridans group streptococci (VGS) LSIE and 48.6% for S. aureus LSIE (enterococci vs VGS: P<0.0001; enterococci vs S. aureus: P=0.02). Enterococcal LSIE patients treated with the combination of a penicillin or vancomycin plus an aminoglycoside (n=60) and those treated with ampicillin plus ceftriaxone (n=6) showed similar in-hospital mortality (26.7% vs 33.3%, P=0.66). High-level resistance to gentamicin was detected in 5 of 38 episodes of enterococcal LSIE (13.1%).

Conclusions: Enterococcal LSIE appears in patients with well-defined clinical characteristics, and causes few peripheral vascular or skin manifestations and few immunological phenomena. The relapse rate is higher than in non-enterococcal LSIE. Mortality due to enterococcal LSIE is lower than that of S. aureus LSIE, and much higher than that of VGS LSIE. Mortality due to enterococcal LSIE is similar in patients treated with ampicillin plus ceftriaxone or with a combination of penicillin or vancomycin plus an aminoglycoside. High-level resistance to gentamicin remains uncommon in enterococci causing LSIE.