darwinian medicine

Rafael Maldonado rafael at howard.genetics.utah.edu
Tue Oct 10 18:11:49 EST 1995

On 9 Oct 1995, Michael F. Hynes wrote:
> What I remember reading somewhere is that if you introduce a plasmid 
> which codes for antibiotic resistance into a bacterium, then you can 
> expect that replicating that plasmid will be costly in metabolic terms 
> and that in the absence of selection, the plasmid will be lost. 
> However, if you grow the bacterium in a chemostat for a lengthy period 
> of time WITH selection, the plasmid seems to adapt itself to its new 
> host, and be maintained afterwards without selection. 

I found this very surprising! Would you like to post some reference for me?

> Getting back to the original article, if the resistance was of the 
> plasmid-encoded type, even if it dwindled to a small frequency in the 
> population, it would rapidly increase as soon as the antibiotic was used 
> again.

Actually, that is true, but anyway this time gap could be enough 
to kill the bacteria by other means.

In countries where have had many antibiotic abuse (Spain is one of 
them), resistant strains are being considered every day in hospitals. The 
idea of stopping administration of common antibiotics (i.e. amoxiciline) 
for a while (several years, I guess), and trying different ones instead has 
been considered, and it is not crazy at all. I remember some 
monograhic issue in Science talking about that few time ago.

I think that antibiotic resistance is a big problem anyway, and that 
bacteria are far superior than us in this fight. 


Rafael Maldonado                             |  La cita ha sido
room 6160 Eccles Institute of Human Genetics |  
Department of Human Genetics		     |  retirada por respeto
University of Utah			     |
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Rafael.Maldonado at genetics.utah.edu           |
Rafael at howard.genetics.utah.edu	             |  intelectual.
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