Tag Archives: disease

Evolution [in]-Action

For general readership

Evolution really happens in nature: we know this from the frightening rate at which bacterial species, faced with our most powerful antibiotics, manage to find ways around them.

More precisely, a certain amount of natural variability and accidental mutations within bacterial populations, and the huge rate at which bacteria reproduce themselves (a single bacterium at dawn may be billions by sunset), essentially assures that eventually, simply by accident, and relatively soon, a bacterium will be “born” that is immune to any particular antibiotic. And then this bacterium, the sole survivor of the onslaught to which its siblings have succumbed, and reproducing by dividing into “children” that also can survive, soon gives rise to a subspecies of its own, against which this antibiotic is useless.  By using the antibiotic again and again, killing off the bacteria from other subspecies, we eventually assure that this unbeatable subspecies becomes more and more common compared to its cousins.

In recent years, bacteria have appeared for which no antibiotic treatment exists.  The rate of the evolution of these bacteria has outpaced the rate at which biologists and medical researchers can find and develop new antibiotic treatments.  The Center for Disease Control is extremely worried about this, and its director Tom Frieden just published a blog post that everyone should read.  Here’s one quotation:

To help draw attention to CRE and other top antibiotic-resistance threats, the Center for Disease Control recently published its first report on the current antibiotic resistance threat to the U.S. The report estimates that each year in the United States, at least 2 million people become infected with bacteria resistant to antibiotics, and at least 23,000 people die as a result.

Note this extraordinary statement: every year, 1 in 150 people in the United States will be infected with bacteria that are resistant to a classic antibiotic every year, and 1% of them will die, some fraction of them because of this resistance.  Let’s put that in perspective: assuming there were no increase in the number of bacteria or improvements in treatment over the next 50 years, your chance of being infected by such a bacterium during that time is roughly 25%.  In short, this will very likely happen to someone you know in the next few years, and someone in your family in coming decades.  (It’s already happened to someone in my extended family.)  And of course, since they are hard to fight, these bacteria are likely to spread, so the rate of infection will become worse if nothing is done.

Here’s another quotation: 

Every doctor must commit to use antibiotics only when needed, and to use antibiotics for only as long as they are needed. Patients need to understand that “more” drugs does not equal “better” drugs. The right treatment is the best treatment – and that isn’t antibiotics for every infection or every illness.

Now why is he making this point so strongly? Let me end by quoting from the preamble to the report he mentions:

The use of antibiotics is the single most important factor leading to antibiotic resistance around the world. Antibiotics are among the most commonly prescribed drugs used in human medicine. However, up to 50% of all the antibiotics prescribed for people are not needed or are not optimally effective as prescribed. Antibiotics are also commonly used in food animals to prevent, control, and treat disease, and to promote the growth of food-producing animals. The use of antibiotics for promoting growth is not necessary,
and the practice should be phased out.

I hope everyone pays close attention to Frieden’s post and its message, and spreads the word among the people that they know.  Doing so may someday help save the life of someone you care about, or even your own.