If you smoke cigarettes, you’re turning MRSA into a super-superbug

smokingThe way we think about smoking and disease is that cigarette smoke causes illness by harming the smoker, for example, by weakening human respiratory and immune cells, by destroying organs such as the lungs, and so on.

While that’s certainly true, researchers at the University of California at San Diego have shown us a second and completely different way in which cigarette smoking will cause disease: by strengthening the pathogen that causes the illness.

The pathogen they used to test their idea was MRSA (Methicillin-resistant staphylococcus aureus). Their method was to prepare 2 batches of it: the “regular” kind, and a second batch of MRSA that was exposed to cigarette smoke. They then infected human cells grown in a lab and live mice with the 2 kinds of MRSA to see if the effects were the same or different. Here’s what they found:

  1. The smoke-exposed MRSA were 4-times harder to kill than regular MRSA.
  2. The effect was dose-dependent, meaning that the more you exposed the MRSA to smoke, the more resistant it became.
  3. The smoke-exposed MRSA were better at invading human and mice cells and causing death. For example, 40 percent of mice infected with the smoke-exposed MRSA died of pneumonia, compared with 10 percent of the mice infected with regular MRSA.

In other words, smoking causes MRSA to be better at both offense and defense: it will kill at a much higher rate, and it’s harder to kill.

In humans, MRSA is typically – and conveniently – found in the nose and airways leading to the lungs. So when you smoke, what you’re doing is you’re bathing these bacteria in the smoke produced by the cigarette, thus turning them into the more potent pathogen that the UCSD experiment demonstrates.

In the fifty years since the first U.S. Surgeon General’s report in 1964 warned us about the link between smoking and lung cancer, nearly 21 million people (the population of Australia) have died prematurely because of smoking or exposure to secondhand smoke.

Or so we thought. In a study reported this February in The New England Journal of Medicine, researchers have added five more diseases and 60,000 deaths a year to the toll taken by tobacco in the United States. For example, compared with people who had never smoked, smokers were about twice as likely to die from infections and respiratory ailments, that were not previously linked to smoking.

Which entitles us to ask a question: What human behavior, including war, causes us more harm than smoking tobacco?

smoking-deaths

 

 

 

 

 

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