Endocarditis Infection Commonly due to Health Care Factors
Jun 27, 2005, 00:21, Reviewed by: Dr.
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"Future educational efforts need to focus on adherence to infection control practices, appropriate antibiotic use, and improving selection of patients for valve surgery. Research efforts are needed to develop more effective bactericidal agents against MRSA and test new adjunctive treatments to reduce the biofilm-producing capabilities of Staphylococcus that make it such a difficult pathogen to eradicate"
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By JAMA/Archives,
An international study reveals that infective endocarditis, infection and inflammation involving the heart valves is commonly associated with health care factors and is increasingly due to staphylococcal infection, according to a study in the June 22/29 issue of JAMA.
For decades, infective endocarditis (IE) caused by Staphylococcus aureus has been viewed primarily as a community-acquired disease, especially associated with injection drug use, according to background information in the article. Because no large, prospectively collected, and geographically diverse cohort of patients with IE existed before now, the global significance and impact of regional variations on the characteristics, treatment, and outcome of S aureus IE has not been known.
Vance G. Fowler, Jr., M.D., M.H.S., of Duke University Medical Center, Durham, N.C., and colleagues conducted a study to document the characteristics of IE caused by S aureus, including IE associated with health care contact and IE due to methicillin-resistant S aureus (MRSA), in different parts of the world; and assessed regional differences and the effect of these differences on clinical outcomes among patients with S aureus IE. The study included 1,779 patients with IE from 39 medical centers in 16 countries. The patients were enrolled in the International Collaboration on Endocarditis-Prospective Cohort Study from June 2000 to December 2003.
The researchers found that S aureus was the most common pathogen among the 1779 cases (558 patients, 31.4 percent). Health care-associated infection was the most common form of S aureus IE (218 patients, 39.1 percent), accounting for 25.9 percent (Australia/New Zealand) to 54.2 percent (Brazil) of cases. Most patients with health care-associated S aureus IE (131 patients, 60.1 percent) acquired the infection outside of the hospital. MRSA IE was more common in the United States (37.2 percent) and Brazil (37.5 percent) than in Europe/Middle East (23.7 percent) and Australia/New Zealand (15.5 percent). Patients in the United States were most likely to be hemodialysis dependent, to have diabetes, to have a presumed intravascular device source, to receive vancomycin, to be infected with MRSA, and to have persistent bacteremia.
"The finding of S aureus as the leading cause of IE differs from previous reports and may be due in part to increasing rates of staphylococcal bacteremia related to health care contact in industrialized nations," the authors write.
"S aureus is now the most common cause of IE in many areas of the developed world. Patients with IE due to S aureus exhibit distinct characteristics compared with patients with IE due to other pathogens. Health care-associated IE is emerging as the most common form of S aureus IE and has distinct features compared with more familiar forms of S aureus IE, such as community-acquired injection drug use-associated infection. MRSA is now encountered internationally as a relatively common cause of IE and is associated with persistent bacteremia. Future investigations are required to identify better treatment and prevention strategies for this serious and common consequence of medical progress," the authors conclude.
ANOTHER STUDY
Despite improvements in health care, the incidence of infective endocarditis in Minnesota has not decreased over 3 decades, according to another study in the June 22/29 issue of JAMA.
Limited data exist regarding population-based epidemiologic changes in incidence of infective endocarditis (IE), according to background information in the article.
Imad M. Tleyjeh, M.D., of Mayo Clinic, Rochester, Minn., and colleagues evaluated trends in the incidence and clinical characteristics of IE in a population-based cohort. The survey was from the Rochester Epidemiology Project of Olmsted County, Minnesota. One hundred seven IE episodes occurred in 102 Olmsted County residents between 1970 and 2000.
Olmsted County is considered an ideal site for a population-based study because the population is relatively isolated from urban centers; medical care is largely self-contained within the community; and medical records of all inpatient and outpatient care are available for study. However, "the population consists largely of middle-class whites, with a low prevalence of injection drug abuse," according to the authors.
"In this geographically defined community, the incidence of IE has remained stable during the past 3 decades. The adjusted incidence of IE ranged from 5.0 to 7.0 cases per 100,000 person-years," the authors write.
The researchers offer 2 potential factors why IE cases have not gone down over the past 30 years. "First, there may have been a true overall decline in IE incidence, which was concealed by a detection bias with better blood culture techniques and more frequent use of echocardiography. Second, an increase in incidence caused by a more frequent use of echocardiography may have been offset, in part, by a declining number of autopsy-diagnosed cases."
In an accompanying editorial, Vincent Quagliarello, M.D., of Yale University School of Medicine, New Haven, Conn., discusses the articles in this week's JAMA on endocarditis.
"What should practicing clinicians learn from the distinct observations of these 2 studies? Although endocarditis is relatively uncommon, it remains a persistent and serious clinical burden in local communities and around the globe. Moreover, in communities where injection drug use is uncommon, viridans streptococci remain a common underlying cause, despite well-known and distributed recommendations for antibiotic prophylaxis. In addition, with increasing insertion of intravascular devices, prosthetic valves, intravenous catheters for outpatient infusion therapy, and patient placement in long-term care facilities, there will be increasing opportunities for patients to become colonized and infected with S aureus, including MRSA. "
"Future educational efforts need to focus on adherence to infection control practices, appropriate antibiotic use, and improving selection of patients for valve surgery. Research efforts are needed to develop more effective bactericidal agents against MRSA and test new adjunctive treatments to reduce the biofilm-producing capabilities of Staphylococcus that make it such a difficult pathogen to eradicate," Dr. Quagliarello concludes. 
- JAMA. 2005;293:3061-3062; JAMA. 2005;293:3022-3028; JAMA.2005;293:3012-3021
http://jama.ama-assn.org/cgi/content/short/293/24/3012
Dr. Quagliarello has served as a paid consultant to Pfizer and Cubist.
This study was supported in part by grants from the Public Health Service and the National Institutes of Health.
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