Cigarette Smoke May Create More Aggressive Antibiotic-Resistant Superbugs

Do you smoke? Then you may be exposing yourself to disease. Scientists have found that the superbug, methicillin-resistant Staphylococcus aureus (MRSA) can become even more resistant to killing by the immune system when exposed to cigarette smoke.

"We already know that smoking cigarettes harms human respiratory and immune cells, and now we've shown that, on the flipside, smoke can also stress out invasive bacteria and make them more aggressive," said Laura Crotty Alexander, one of the researchers, in a news release.

Methicillin-resistant MRSA is an antibiotic-resistant superbug. It can cause life-threatening skin, bloodstream and surgical site infections and pneumonia. In this case, Crotty Alexander noticed that many of her patients who smoked cigarettes also had MRSA infections, and wondered if one might influence the other.

In order to find out, the researchers infected macrophages, which are immune cells, with MRSA. Some of the bacteria were grown normally and some were grown with cigarette smoke extract. The scientists found that while the macrophages were equally able to take up the two bacterial populations, they had a harder time killing the MRSA that had been exposed to the cigarette smoke extract.

But why is this? The scientists found that once inside macrophages, the smoke-exposed MRSA were more resistant to killing by reactive oxygen species, the chemical burst that macrophages use to destroy their microbial meals.

"Cigarette smokers are known to be more susceptible to infectious diseases," said Crotty Alexander. "Now we have evidence that cigarette smoke-induced resistance in MRSA may be an additional contributing factor."

The findings are published in the journal Infection and Immunity.

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