Heart infection linked to Staph bacteria

WASHINGTON, Jun 21, 2005 (United Press International via COMTEX) -- An international study suggests a growing number of cases of infective endocarditis -- a potentially deadly infection of the heart valves -- stem from healthcare settings, and the most common cause is a strain of bacteria growing increasingly resistant to medications used to treat the illness.

Infective endocarditis previously had been thought to be due primarily to injection drug use and other factors not associated with healthcare facilities, but the new study -- which involved nearly 1,800 patients in 16 countries -- indicates patients may become infected during various hospital and out-patient procedures, and a bacteria known as Staphylococcus aureus plays a major role.

"Staphylococcus aureus is now the most common cause of endocarditis in many parts of the world," Dr. Vance Fowler of Duke University Medical Center in Durham, N.C., an author of the study, told United Press International.

"The primary risk factors for these patients ... appear to (involve) healthcare contact," Fowler said.

He added that many patients in the United States with this condition appear to have acquired it outside of the formal hospital setting, such as at hemodialysis clinics and nursing homes.

"These findings are significant because Staphylococcus aureus ... is more virulent and harder to treat and increasingly resistant to our available antibiotics," Fowler said, meaning there might be no way to treat some patients.

In the study, which appears in the June 22/29 issue of the Journal of the American Medical Association, Fowler and colleagues found S. aureus was the most common pathogen infecting the 1,779 study patients, encompassing 558 or 31 percent.

The team also found the healthcare setting was the most common source of the infection in other countries, ranging from 26 percent of cases in Australia/New Zealand to about 54 percent in Brazil. Most of the patients who acquired endocarditis via S. aureus, however, did so outside of the hospital.

A drug-resistant strain known as methicillin-resistant S. aureus, or MRSA, was the most common in the United States and Brazil, accounting for 40 percent of infections in some regions.

MRSA is a growing problem in the United States, both in and out of hospital, and it has caused outbreaks in several states.

In an accompanying editorial, Dr. Vincent Quagliarello of Yale University School of Medicine in New Haven, Conn., wrote that with modern healthcare procedures there will be increasing opportunities for patients to acquire infections that cause endocarditis, 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," Quagliarello wrote. "Research efforts are needed to develop more effective bactericidal agents against MRSA," he added.

Last week the Food and Drug Administration may have taken a step that will help combat endocarditis due to MRSA. The agency approved a new antibiotic called Tygacil that manufacturer Wyeth Pharmaceuticals said is effective against MRSA.

Fowler said Tygacil would help, but he did not think it would be a total solution.

"While no single antibiotic is going to solve the problem of MRSA," he said, "each of these new anti-microbials that are added to our arsenal of treatments are important steps in the right direction."

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