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Superbugs and evolution in action
By Crobar in Neurognosis
October 23, 2007

People often ask me for proof of evolution "in action" or "happening now".  After reading current stories in newspapers and online about the new deadly strain of anti-biotic resistant Staphylococcus aureus, it makes my job in those instances easier - just e-mail them the news stories.

A new strain of resistant Staph has been noticed - a "superbug".  A superbug is a strain of bacteria or other microorganism (bacteria are often referred to as "bugs") that is extremely resistant to first line medications (such as antibiotics).  These can be common bacteria which are known for being easy to treat.  However, we see evolution through natural selection work and what happens?  Superbugs.

This is shown through the numbers from a paper authored by Jaime Fergie and Kevin Purcell in the journal Pediatric Annals.  The strain is referred to as Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA).  In the article, Fergie and Purcell state that:

"Since the first case reports of methicillin-resistant S. aureus (MRSA) infections in the United States in 1968, MRSA has become an increasing problem, now accounting for 50% or more of the nosocomial S. aureus isolates nationwide."

Source - Fergie, J. and Purcell, K. (2007). The Epidemic of Methicillin-Resistant Staphylococcus aureus Colonization and Infection in Children: Effects on the Community, Health Systems, and Physician Practices. Pediatric Annals, 36, 402-412.

I'd say that constitutes a problem.

So how does this happen?  Well folks, it's "evolution in action".  Let's take a single person who has a bacterial infection.  The person goes to their physician who prescribes an appropriate antibiotic.  The person is instructed to take all the antibiotics even if they feel better.  Let's say John Doe feels better after a couple of days and stops taking the meds.  Well, what John doesn't realize is that he's killed off the least resistant bacteria but they aren't all gone (and still enough to keep his immune system busy, busy, busy - which is why extra help is needed).  The bacteria who are more resistant to the antibiotics are the ones that are left and then they begin to reproduce.  John starts to feel sick again and even worse than before.

With our societies use of anitbiotics we've saved untold millions of lives.  However, there's always those little bugs which are genetically configured with the ability to be unfazed by the medications.  These are the little bugs that reproduce and create their own little communities of drug resistance - superbugs.  Natural selection worked in this instance to select for organisms with heightened resistance to antibiotics and over time we get the prevalence of these superbugs rising - evolution in action.

The strains of staph aren't the only ones and this isn't a recent thing.  The prevalence of such strains has been steadily rising over the past several decades.  So if there's someone who wants "proof" of "evolution in action" or evolution itself - there you have it, ripped from the headlines.