Antibiotics to stop stroke?

Main Category: Stroke / Neuroprotection
Article Date: 11 Aug 2003 - 0:00 PDT

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A new study hints that antibiotics may work to prevent stroke in elderly people with hypertension.

Both the authors of the study, appearing in the September issue of Stroke, and outside experts caution that the results are extremely preliminary.

There are lots of residual things that we might not have accounted for that could have explained some of the findings, says study author Dr Paul Brassard, a clinical researcher at McGill University Health Centre in Montreal.

Not dramatic, but still significant

The study is not particularly dramatic, echoes Dr Keith Siller, director of the New York University Comprehensive Stroke Care Center. Whenever you document an association you don't know whether there's a third factor that's really influencing this.

The findings may, however, bolster the theory that infections may contribute to inflammatory processes underlying strokes and heart attacks.

The role of infection in heart disease and stroke

Some studies have suggested that infections may be linked to heart disease and stroke and that, specifically, atherosclerosis (fatty build-up in the walls of arteries) may be a chronic inflammatory condition.

Treating the cause, the theory holds, might prevent the onset of cardiovascular disease or slow its progression. In this case, it reinforces our idea that there is an inflammatory reaction that is part of the atherosclerotic plaque, Siller says.

Scientists already know that inflammation is involved in vascular disease. It's just not clear what causes the inflammation or how the mechanism works precisely.

This just adds to the overall body of evidence that infection might contribute one way or another, Brassard says.

The research study

The study team looked at the health records of 1 888 patients who had been treated for hypertension and had had a stroke. They were then compared with 9 440 hypertensive individuals who had not had a stroke.

The researchers also looked to see which patient had used antibiotics and when.

Any antibiotic use was associated with a slightly decreased risk of stroke, but the relationship was not statistically significant except in the case of penicillin. The most striking results were in current penicillin users, who were 47 percent less likely to have a stroke, relative to people who had not used antibiotics.

Even in the case of penicillin, the absolute numbers were low - 1,1 percent of stroke patients were current users, versus only 1,7 percent of the controls - and Brassard is not ruling out the possibility that this was a random occurrence.

Treatment possibilities not clear yet

Right now, researchers are awaiting the results of trials that are looking at antibiotic use in people who have already had a stroke or heart attack.

But even if those trials and others do show a cause-and-effect relationship between antibiotics and stroke prevention, it's not clear how this will affect treatment.

It would open a big black box, Brassard admits. Before prescribing antibiotics to patients, doctors would have to seriously consider not only the individual but also the public health implications, as excessive antibiotic use contributes to bacterial resistance and makes future infections harder to treat.

There are so many reasons not to use antibiotics, Siller says. Certainly, they wouldn't be any kind of substitute for the standard therapy we have now, which is primarily blood thinners and reducing risk factors.

But that bridge, if ever we need to cross it, is really, really, really down the road, Brassard says.