Impact of Regional Comorbidity on Infective Endocarditis in a Southeastern United States Medical Center

Introduction: Recent reports differ regarding microbiologic and epidemiologic characteristics of infectious endocarditis (IE). The authors studied cases presenting to our institution from 2001 to 2006, hypothesizing regional variation in patient populations and comorbidity (especially end-stage renal disease) significantly impact IE causative factors and presentation, which may account for conflicting reports in the literature. Methods: Consecutive IE cases were prospectively identified and characterized. Multivariate logistic regression analysis identified factors associated with Staphylococcus aureus IE. Incidence of IE in populations on and not on hemodialysis (HD) was estimated, and relative frequency of IE in the population requiring HD was calculated. Results: Of 160 cases, infection was community acquired in 48.8%, nonnosocomial healthcare-associated in 35.6% and nosocomial in 15%. S aureus caused infection in 47.5%. No contribution of referral bias to the predominance of S aureus infection was detected. Factors significantly associated with S aureus infection included symptom duration < 1 month, HD and persistent bacteremia. Transthoracic echocardiography was less sensitive in detecting IE in community-acquired infection in comparison with nosocomial infection (P = 0.0383). Estimation of IE incidence in the population on HD relative to the population not on HD revealed a 129- to 174-fold increased incidence of IE in this population. S aureus caused IE in 76.2% of patients on HD. Conclusion: S aureus is the most frequent cause of IE at our Southeastern institution. Healthcare-associated acquisition, particularly HD, influenced this epidemiological trend. In populations with a high prevalence of HD, the epidemiology of IE may reflect the increased incidence of HD-associated IE caused by S aureus.