Left-sided native valve endocarditis by coagulase-negative staphylococci: an emerging disease

OBJECTIVES. To describe the epidemiological, clinical, and prognostic characteristics of patients with left-sided native valve endocarditis (LNVE) caused by coagulase-negative staphylococci (CONS). PATIENTS AND METHOD. Prospective multicenter study of endocarditis cases reported in the Andalusian Cohort for the Study of Cardiovascular Infections between 1984 and 2005. RESULTS. Among 470 cases of LNVE, 39 (8.3%) were caused by CONS, a number indicating a 30% increase in the incidence of this infection over the last decade. The mean age of affected patients was 58.32+/-15 years and 27 (69.2%) were men. Twenty-one patients (53.8%) had previous known valve disease and half the episodes were considered nosocomial (90% of them from vascular procedures). Median time interval from the onset of symptoms to diagnosis was 14 days (range: 1-120). Renal failure (21 cases, 53.8%), intracardiac damage 0 1 cases, 28.2%), and central nervous system involvement (10 cases, 25.6%) were the most frequent complications. There were only 3 cases (7.7%) of septic shock. Surgery was performed in 18 patients (46.2%). Nine patients (23.1%) died, overall. Factors associated with higher mortality in the univariate analysis were acute renal failure (P = 0.023), left-sided ventricular failure (P = 0.047), and time prior to diagnosis less than 21 days (P = 0.018). As compared to LNVE due to other microorganisms, the patients were older (P = 0.018), had experienced previous nosocomial manipulation as the source of bacteremia (P < 0.001), and developed acute renal failure more frequently (P = 0.001). Mortality of LNVE due to CoNS was lower than mortality in Staphylococcus aureus infection, but higher than in Streptococcus viridans infection. CONCLUSIONS. Left-sided native valve endocarditis due to CONS is now increasing because of the ageing of the population. This implies more frequent invasive procedures (mainly vascular) as a consequence of the concomitant disease. Nonetheless, the mortality associated with LNVE due to CoNS does not seem to be greater than infection caused by other pathogens.