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Infectious heart disease death rates rising again say scientists

September 11, 2008

Infectious heart disease is still a major killer in spite of improvements in health care, but the way the disease develops has changed so much since its discovery that nineteenth century doctors would not recognize it, scientists heard today (Thursday 11 September 2008) at the Society for General Microbiology's Autumn meeting being held this week at Trinity College, Dublin.

Infective endocarditis is a devastating, progressive and frequently fatal heart disease usually caused by bacterial pathogens. It was first identified in the nineteenth century and has changed beyond all recognition due to evolution of the disease itself and developments in modern healthcare such as open-heart surgery, antibiotics and new medical imaging techniques.

"In spite of these medical advances, infective endocarditis is still evolving and we are seeing new patterns of the disease and its complications. Despite all our improvements in health care, the death rate has been virtually unchanged for the last 20 years, and now seems to be rising again," said cardiologist Dr Bernard Prendergast from the John Radcliffe Hospital in Oxford, UK.

"In the nineteenth century rheumatism affecting the heart valves was the most common form of heart disease and the usual target for infective endocarditis. 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," said Dr Prendergast. "On top of that, aggressive Staphylococcus infections are now common, and conventional antibiotic treatments are becoming less effective because of drug-resistant bacteria".

Early surgery to treat valve infection would probably save many lives. However, the operations needed are often tricky and high risk because patients are extremely sick at the time of surgery. For this reason, the timing of the operation can be difficult and expert care is essential.

A second controversy is whether patients with valve disease can be protected from the risk of infection at the time of routine procedures such as dental work by using preventative antibiotic treatment. While this has been traditional practice, recent assessment by the government watchdog NICE, has suggested that this practice is obsolete, although this recommendation is in conflict with the position in the USA and Europe.

"It's an impossible and continuing debate, fueled by fundamental differences in international guidelines," said Dr Prendergast. "We just don't have the results from properly conducted and randomized clinical trials to know whether routine prophylactic antibiotics are helpful or not. Greater awareness of the dangers of infective endocarditis amongst both doctors and patients is certainly essential and improved dental health and skin hygiene are probably at least as important as blanket antibiotic treatment. As the disease evolves even further this debate could run on for years with heart physicians, microbiologists and surgeons all having different opinions. This is very unhelpful and confusing for patients."

Society for General Microbiology