August 22, 2017 | David F. Coppedge

Antibiotic Resistance Moves from Evolution to Design

They can call it evolution, but information sharing is not what Darwin had in mind.

“MRSA emerged years before methicillin was even discovered” proclaims an article on Science Daily. At least 14 years before the last-ditch antibiotic was produced to fight this resistant bacterial strain. This implies that selection pressure was not responsible for making methicillin resistant Staphylococcus aureus (MRSA) “evolve” somehow, because it already existed. But how did this resistance emerge in the first place? The article calls these “pre-existing adaptations in the bacterial population,” but that doesn’t answer the question.

To uncover the origins of the very first MRSA and to trace its evolutionary history, the researchers sequenced the genomes of a unique collection of 209 historic S. aureus isolates. The oldest of these isolates were identified over 50 years ago by the S. aureus reference laboratory of Public Health England and have been stored ever since in their original freeze-dried state. The researchers also found genes in these isolates that confer resistance to numerous other antibiotics, as well as genes associated with decreased susceptibility to disinfectants.

So the genes for resistance already existed. Bacteria are also known to share information by horizontal gene transfer, which would be a clever design for sharing ways to defeat harmful substances they had not encountered before. The article claims these adaptations evolved, but had no evidence that resistance was already in the microbial population. It might be like house locks. Those without the locks pre-installed could avoid being burglarized, by having obtained the locks in advance.

At The Conversation,┬áPredrag Slijepcevic says that bacterial colonies have their own kind of internet. “When resources are exhausted in one place, microbial expedition forces advance to find new lands of plenty,” he says. “They transmit their discoveries back to base using different kinds of chemical signals, calling for microbial society to transform from settlers to colonisers.” This ability to transmit information sounds more like design than Darwinian evolution, which could not wait for lucky beneficial mutations to appear. Instead, it sounds like the cells come with tools to quickly solve problems in new environments, and then communicate those solutions to the colony.

For more on antibiotic resistance, see Jonathan Wells’s new book Zombie Science, chapter 8.

 

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