Despite medical improvements, the rate for infective endocarditis has been virtually unchanged for last 20 years, and now seems to be rising again, Dr. Bernard Prendergast of Oxford, England's John Radcliffe Hospital told a meeting of the Society for General Microbiology held at Trinity College, in Dublin, Ireland.

"Now that people live so long, degenerative heart valve disease is a more common problem. We're also seeing complications in patients who have received replacement heart valves and infections as a result of intravenous drug use," Prendergast said in a statement. "On top of that, aggressive Staphylococcus infections are now common, and conventional antibiotic treatments are becoming less effective because of drug-resistant bacteria."

Presently, early surgery to treat valve infection is controversial as is preventative antibiotic treatment, Prendergast said.

"We just don't have the results from properly conducted and randomized clinical trials to know whether routine prophylactic antibiotics are helpful or not," Pendergast said. "Improved dental health and skin hygiene are probably at least as important as blanket antibiotic treatment."