P.S. My final quarter had a directed research project for which I wrote my final paper entitled “Ethics THROUGH Evolution”.

I apologize for the obliquity.

“The actual mechanism of antibiotic resistance is usually mediated by a mutation which makes the pathogen LESS fit.”

Let me get this right: A bacteria that survives in its antibiotic drenched environment is LESS fit than one that does not survive???

Evolutionary principles are also critical in studying the molecular biology of disease. Genetic information that has been conserved throughout evolution points out protein domains with important functions, and understanding the evolutionary lineage of genes helps us use animal models to study the causes of disease and identify therapeutic targets.

Thank you for this, Dr. Novella.

Here is the comment again.

“Now we live in a largely hygienic environment, and have even taken steps to eliminate parasites. This may have unintentionally deprived our immune systems of needed stimulation, resulting in poor immune regulation, and subsequent increase in auto-immune diseases like asthma and multiple sclerosis.”

“I seem to recall Bill Maher and George Carlin both making similar statements, that it’s better to keep an immune system challenged versus being too obsessive about vaccinations or hygiene, respectively. meh.”

The difference, of course, is that the first statement is an emerging hypothesis based on empirical evidence and a firm understanding of Immunology. Still, more work needs to be done to validate it and to come up with a useful, scientifically proven intervention, if that is even possible.

On the other hand, Maher’s statement is based on pure intuition which completely lacks an understanding of Biology. There is no empirical evidence for his claim.

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On the other hand, Maher’s statement is based on pure intuition which completely lacks an understanding of Biology. There is no empirical evidence for his claim.

The actual mechanism of antibiotic resistance is usually mediated by a mutation which makes the pathogen LESS fit. It usually involves a partial destruction of a trait, rather than formation of a new and improved one.

Consider sulfadoxine which inhibits the enzyme DHPS. A mutation in the enzyme makes the enzyme less efficient, but is selected for in an antibiotic environment because that mutation is thought to change the conformation of the enzyme. The new conformation no longer binds to the antibiotic, rendering the antibiotic ineffective.

The evidence demonstrating this is straight forward. When the antibiotic is no longer present, the more efficient version of the enzyme returns in full force. The less fit mutant strain dies out. This is why community acquired infections are usually much easier to treat (because they have less antibiotic resistance) than hospital acquired ones. (Obviously, MRSA would be one example of an important exception.)

So it is usually not an “arms race” that is observed when you look at antibiotic resistance in real time. Instead it is more like a “scorched earth strategy”: the defender escapes because of the destruction of its own internal machinery, a phenomenon mediated mutation and selection.

http://www.sciencedaily.com/releases/2005/06/050602012109.htm

“I seem to recall Bill Maher…making similar statements, that it’s better to keep an immune system challenged versus being too obsessive about vaccinations…”

I suppose you told him that vaccinations, like the microorganisms they protect against, also challenge the immune system but with enormously less risk of harming or destroying the body.

“It has been known for a long time that sickle-cell trait provides resistance to malaria (the blood cells are less hospitable to the P. falciparum bacteria that is one cause of malaria).”

P. falciparum is a type of protozoan, not a bacterium.

I had a guest in my Biology of Infectious Diseases class come in and talk about why Malaria is just so damned hard to create a vaccine for, and one of the reasons (among others) is because P. falciparum (et. al.) aren’t “simple” bacteria. All that damned sexual + asexual reproduction. And to think one of the theories for the emergence of sexual reproduction was to combat parasites .

Oh, and this is my first post. Love the Blogs + SGU!

Now we live in a largely hygienic environment, and have even taken steps to eliminate parasites. This may have unintentionally deprived our immune systems of needed stimulation, resulting in poor immune regulation, and subsequent increase in auto-immune diseases like asthma and multiple sclerosis.

I seem to recall Bill Maher and George Carlin both making similar statements, that it’s better to keep an immune system challenged versus being too obsessive about vaccinations or hygiene, respectively. meh.

The opposite is true too. Antibiotic resistance is a great example of evolution by natural selection occurring before our very (microscope-aided) eyes.

Hmm, I wonder if controlled intestinal parasite infection to prevent auto-immune disease would be an even tougher sell than maggot debridement therapy.