ICAAC: Statins also Battle Bacteria and Fungi

CHICAGO, Sept. 21 -- Statins, widely used for their anti-cholesterol properties, also appear to have anti-microbial and anti-fungal properties, researchers said here.

That finding may explain, in part, why some observational studies have found that statin users are less susceptible to infections, according to Jon Cohen, MBBS, of Brighton and Sussex Medical School in Brighton, England.

The anti-bacterial effect -- seen so far only in the lab -- is "modest" and doesn't mean that statins can be used as antibiotics, Dr. Cohen told attendees at the Interscience Conference on Anti-microbial Agents and Chemotherapy.

But it may point the way to new antibiotics derived from the statins, he said.

"If the chemists were to go away and play with the structure of these drugs, they might be able to come up with new antibiotics," he said.

Robert Akins, Ph.D., and colleagues at Wayne State University School of Medicine in Detroit, also presented data on the topic, confirming the British finding and extending it to fungi.

But Dr. Akins said he agrees with Dr, Cohen that, while commercial statins are unlikely to be useful as antibiotics, they might be the starting point for rational design of new medications that would work better.

Researchers and physicians have known for several years that people taking statins have an unexpected resistance to infection. Indeed, at this meeting in 2001, a retrospective look at more than 9,000 patients showed that diabetic veterans taking statins had a 19% reduction in the risk of lower extremity infections, compared with those not on the drugs.

But that effect, also seen in other observational studies, could have two explanations, Dr. Cohen said: The statins might be somehow improving the immune response or they might be fighting pathogens directly.

He and a colleague decided to test the second idea, using simvastatin (Zocor) and fluvastatin (Lescol) against methicillin-sensitive and --resistant Staphylococcus aureus and vancomycin-sensitive and --resistant Enterococci.

Simvastatin showed a noticeable antimicrobial effect against sensitive S. aureus with an average minimum inhibitory concentration of 29.2 milligrams per liter. The drug also inhibited the resistant bacteria, although more was needed, as well as vancomycin-resistant enterococci.

Fluvastatin, on the other hand, had little effect, he said.

Dr. Akins and colleagues, testing a wider range of drugs and bacteria, also found that "individual statins varied in the range of species affected."

For instance, he said, simvastatin, lovastatin (Mevacor), and atorvastatin (Lipitor) all inhibited Bacillis subtilis, but none of them inhibited Escherichia coli.

Dr. Akins and colleagues also reported that statins can inhibit a range of Candida species, although the minimum inhibitory concentrations are, again, so high that commercial drugs would not be useful anti-fungal agents.

But the statins differ markedly in their ability to inhibit fungi, which "suggests that rational, structure-based modifications to current statins have the potential to dramatically increase their antifungal activity," Dr. Akins said.

On the other hand, Dr. Cohen said that the existing effect might be enough to prevent an infection, even though it wouldn't be powerful enough to cure disease.

"It could be that pre-existing statins (in the bloodstream) might prevent an infection from catching on," he said.

Both Dr. Akins and Dr. Cohen said more work is needed, especially to tease out exactly how the inhibitor effect takes place.