Two large studies have reached the conclusion that regularly taking antibiotics does not prevent heart disease as some scientists had hoped the drugs would.
This had been a promising strategy because a great deal of research has linked a common respiratory germ to heart attacks and clogged arteries. The germ still may help trigger heart disease, but once people have the condition, attacking the bug does not cut their risk of future heart problems, the studies found.
They were published in today's New England Journal of Medicine.
The germ is Chlamydia pneumoniae, but other than being in the same family of bacteria, it has no relation to the sexually transmitted disease chlamydia.
In one study, led by Dr. J. Thomas Grayston of the University of Washington in Seattle, 4,012 people who already had suffered a heart attack or clogged artery problem were given either azithromycin or a placebo once a week for a year.
Nearly four years later, the number of heart attacks, deaths, hospitalizations, and necessary additional heart procedures was almost identical between the groups.
The other study tested a different and theoretically more powerful drug, gatifloxacin, on people recently hospitalized for a heart problem.
Doctors gave 4,162 patients 10 days of either the drug or dummy pills monthly for two years on average. Again, the results were very similar.
The studies ''reinforce the importance of using proven therapies" such as cholesterol-lowering statin drugs in such patients, said the researchers, led by Dr. Christopher Cannon of Brigham and Women's Hospital and Harvard Medical School in Boston.