TUESDAY, June 21, 2005 (HealthDay News) -- For years, doctors have associated the inflammatory heart valve condition infective endocarditis with risk factors such as injection drug use and infection with the streptococcus family of bacteria.
But a new international study points to infection with the much harder-to-treat Staphylococcus aureus bacteria as an increasing cause of infective endocarditis, much to the researchers' alarm. It also found that many of these infections may be occurring in hospitals, nursing homes and other health-care settings.
"The face of endocarditis, a potentially lethal infection of the heart, has changed fundamentally, in terms of the organism responsible," said lead researcher Dr. Vance G. Fowler Jr., an assistant professor of medicine at Duke University Medical Center. His team published their findings in the June 22/29 issue of the Journal of the American Medical Association.
Staphylococcus aureus was found to be the most common cause of infection among the 1,779 patients in the 16 countries covered by the study, the report found.
That change has important implications for medical practice, since more and more strains of staph are resistant to the most widely used antibiotics, Fowler said.
"S. aureus is a highly virulent pathogen," he explained. "The pipeline of effective antibiotics against S. aureus is dwindling, leaving us with less therapeutic options in a setting of greater clinical need."
Another report in the same issue of the journal was at odds with Fowler's study, however.
Physicians at the Mayo Clinic looked at all 102 cases of infectious endocarditis occurring in Olmsted County, Minn., between 1970 and 2000. They concluded that there has been no increase in staph infections at their center.
The study found the incidence of the infection had not increased over the decades, said Dr. Imad M. Tleyjeh, an instructor in medicine at the Mayo and lead author of the report. "The second finding is that streptococcus infections remain more common than staph infection," he said. But he acknowledged that "other studies say that staph is taking over."
The finding that endocarditis infections can result from medical care and yet often occur to people who are not hospitalized is a result in a change in medical practice, said Dr. Vincent Quagliarello, a professor of medicine at Yale University, who wrote an accompanying editorial on the studies
"What has happened over the past couple of decades is that more and more people are being treated in an ambulatory setting," Quagliarello said. "They may be in a nursing home, getting chemotherapy, on dialysis. They may not be in a hospital, but they have a lot of contact with the hospital system."
Doctors need to recognize the change in the pattern of these infections, Quagliarello said. "They used to be seen almost exclusively in the hospital," he said. "Now, you see patients arriving with it in the emergency room. If there is a suspicion of bacterial infection, there should be recognition that it may be a resistant infection."
More information
For more on resistant staph, visit the CDC.
