Cigarette smoke makes superbugs deadlier

Washington: A new study has demonstrated that an antibiotic-resistant superbug called Methicillin-resistant Staphylococcus aureus (MRSA) can be more aggressive and dangerous due to cigarette smoke.

The study conducted at University of California suggested that the drug can cause life-threatening skin, bloodstream and surgical site infections or pneumonia and it can be worse if it comes in contact with cigarette smoke.

Senior author Laura E. Crotty Alexander, MD, assistant clinical professor of medicine at UC San Diego, asserted that they already knew that smoking cigarettes harms human respiratory and immune cells, and now they had shown that, on the flipside, smoke could also stress out invasive bacteria and make them more aggressive.

Crotty Alexander and her team infected macrophages, immune cells that engulf pathogens, with MRSA. Some of the bacteria were grown normally and some were grown with cigarette smoke extract and they 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 cigarette smoke extract.

Alexander's team tested the bacteria's susceptibility to individual mechanisms macrophages typically employ to kill bacteria. Once inside macrophages, smoke-exposed MRSA were more resistant to killing by reactive oxygen species, the chemical burst that macrophages use to destroy their microbial meals.

The team also discovered that smoke-exposed MRSA were more resistant to killing by antimicrobial peptides, small protein pieces the immune system uses to poke holes in bacterial cells and trigger inflammation and the effect was dose-dependent, meaning that the more smoke extract they used, the more resistant the MRSA became.

Alexander said that cigarette smokers were known to be more susceptible to infectious diseases and now they had the evidence that cigarette smoke-induced resistance in MRSA may be an additional contributing factor.