1. Home>
2. Specialties>
3. Infectious Diseases>
4. Summary and Comment

New Insights into the Epidemiology of Endocarditis

Two rigorously performed studies provide differing perspectives on the epidemiology of endocarditis.

The past 40 years have seen major changes in the epidemiology and clinical manifestations of infective endocarditis in the developed world. However, a detailed analysis of these changes has been lacking. Two new studies afford a better understanding of the trends in infective endocarditis overall and Staphylococcus aureus endocarditis in particular.

Tleyjeh and colleagues reviewed all 107 cases of infective endocarditis that occurred in the relatively isolated community of Olmsted County, Minnesota, from 1970 through 2000. Patients were 18.8 to 90.6 years old (mean, 61.5 years); 73% were male; only 3% were injection-drug users. During these 30 years, the age-adjusted incidence varied between 5.0 and 7.0 cases per 100,000 person-years. The proportion of cases involving aortic valves or occurring in patients with past rheumatic fever trended downward, whereas the proportion occurring in patients with mitral valve prolapse or prosthetic valves increased. The principal causative organisms were viridans group streptococci (44%) and S. aureus (26%); no significant variation over time was noted.

Fowler and colleagues undertook a prospective analysis of S. aureus endocarditis cases seen at 39 medical centers in 16 countries from June 2000 through December 2003. Staphylococcus aureus was the pathogen identified most frequently (558 of 1779 cases; 31.4%). Clinical characteristics independently associated with S. aureus endocarditis (as compared with endocarditis due to other pathogens) were injection-drug use, symptoms for <1 month before presentation, healthcare-associated infection, persistent bacteremia, infection linked to an intravascular device, stroke, and diabetes mellitus. Healthcare-associated infections represented 39% of S. aureus infections, with 60% of these acquired in a hospital and 40% in other settings. Compared to community-acquired S. aureus cases with (CA-IDU) or without (CA-nonIDU) injection-drug use, healthcare-associated cases were associated with higher inpatient mortality (29% vs. 11% [CA-IDU] vs. 21% [CA-nonIDU]), a higher rate of methicillin-resistant S. aureus (MRSA) infections (49% vs. 10% vs. 13%), and a higher rate of mitral-valve infections (56% vs. 20% vs. 49%). Clinical features independently associated with MRSA infection were healthcare-associated infection, chronic immunosuppressive therapy, infection linked to an intravascular device, persistent bacteremia, and diabetes mellitus.

Comment: As noted by an editorialist, these two rigorously performed studies provide differing perspectives on endocarditis. Tleyjeh and coworkers’ study spanned 3 decades, investigated disease in a primarily middle-class population not involved with injection-drug use, and found relatively stable disease characteristics. In contrast, Fowler and colleagues focused on cases that occurred within the last 5 years and highlighted emerging issues including increasing rates of healthcare-associated infections and of MRSA infections.

— Richard T. Ellison III, MD

Published in Journal Watch Infectious Diseases July 22, 2005

Citation(s):

Tleyjeh IM et al. Temporal trends in infective endocarditis: A population-based study in Olmsted County, Minnesota. JAMA 2005 Jun 22/29; 293:3022-8.

• Original article (Subscription may be required)
• Medline abstract (Free)

Fowler VG Jr et al. Staphylococcus aureus endocarditis: A consequence of medical progress. JAMA 2005 Jun 22/29; 293:3012-21.

• Original article (Subscription may be required)
• Medline abstract (Free)

Quagliarello V. Infective endocarditis: Global, regional, and future perspectives. JAMA 2005 Jun 22/29; 293:3061-2.

• Original article (Subscription may be required)
• Medline abstract (Free)