Emergence of methicillin resistance predates the clinical use of antibiotics - Nature
Methicillin-resistant strains of Staphylococcus aureus appeared in European hedgehogs in the pre-antibiotic era as a co-evolutionary adaptation to antibiotic-producing dermatophytes and have spread within the local hedgehog populations and between hedgehogs and secondary hosts.
Ilia ❄️

I just wanted to note 3 remarkable things about natural selection (actually these are the lessons we learn from drug-resistant pathogens):

  • Natural selection is a process of editing, not a creative mechanism. A drug does not create resistant pathogens; it selects for resistant individuals that are already present in the population.
  • In species that produce new generations in short periods of time, evolution by natural selection can occur rapidly.
  • Natural selection depends on time and place. It favors those characteristics in a genetically variable population that provide an advantage in the current, local environment. What is beneficial in one situation may be useless or even harmful in another.

Doesn’t the over use of methicillin excelerate the rate of resistant bacteria?


Yes, it does! This paper shows an example of the presence of populations of antibiotic resistant bacteria in the wild. These populations thrive on the skin of hedgehogs infected with a fungus that produces the antibiotic. The over use of antibiotics applies a new selection pressures that allows antibiotic resistant bacteria to thrive, so their populations increase.

Exactly how these resistant bacteria come to exist is not always clear. Resistant bacteria can emerge via new mutations, gene transfer, or they may already be present in the wild. As this work shows, at least some strains of resistant Staphylococcus aureus probably come from the wild.

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