Introduction: Changes in the etiology, epidemiology, and outcome of infective endocarditis (IE) have been observed in recent years. Newer invasive therapeutic interventions have increased the risk of bacteremia and nosocomial endocarditis in the population at risk. A retrospective analysis of hospital-acquired IE cases was performed in a tertiary hospital during 1985 to 1999.
Material and methods: Cases included were those classified as "probable" or "definite" by the IE diagnostic criteria of Durack. Nosocomial acquisition was considered if diagnosis was made > 72 h after hospital admission and there was no evidence that IE was present at the time of admission. Patients receiving a diagnosis within 60 days of a previous hospital admission were also classified as nosocomial, when a risk procedure for bacteremia was performed, or when any predisposing factor for IE was present during hospitalization. Early prosthetic valve endocarditis (PVE) cases (< 1 year) were excluded from the analysis. Clinical characteristics, etiology, predisposing cardiac condition, source of infection, and outcome were analyzed. Results were compared with those obtained in community-acquired cases.
Results: Of 493 cases of IE diagnosed over 15 years, 38 were considered to be hospital acquired. Twenty-eight cases were native valve endocarditis (NVE) in non-IV drug user patients, and 10 cases were late PVE. Overall, the most frequent microorganisms involved were staphylococci (58%). The main sources of infection were intravascular procedures or catheter-related infections (55%). When nosocomial NVE cases were compared with community-acquired cases, mortality was greater (29% vs 9.7%) in hospital-acquired endocarditis. Analysis of time trends showed an increased rate of nosocomial cases in NVE throughout the years of the study.
Conclusions: In NVE, the number of cases that are hospital acquired has been increasing during the last 15 years. These cases are frequently associated with invasive intravascular procedures or IV catheter-related infections. Most patients have a previous valvulopathy that predisposes to IE. The spectrum of microorganisms involved is different from the community-acquired cases. Also, the outcome of endocarditis is worse in nosocomial NVE patients.