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== Microevolution in Bacteria ==

== Microevolution in Bacteria ==

Microevolution is the process by which bacteria develop resistance to antibiotics.  When a colony of bacteria is exposed to an antibiotic, most of the bacteria die.  However, in some cases a few bacteria have randomly mutated, usually through mistakes in copying the RNA during cell division.  By pure chance, some of these mutations might include a strain of RNA that makes that particular bacterium resistant to the antibiotic.  This one bacterium is then able to reproduce where the others can't.  The actual probablility of a random mutation creating a bacterium that is resistant to a particular antibiotic is exptremely small, but in some cases, the number of bacteria involved is sufficient to offset the odds.

Microevolution is the process by which bacteria may develop resistance to antibiotics.  We regularly use antibiotics to stop bacterial infections.  When a colony of bacteria is exposed to an antibiotic, the bacteria are likely to die if they do not have genes that produce molecules to inhibit the action of the antibiotic.  If the survivors reproduce, the colony will contain mostly bacteria that have inherited resistance genes.  A second application of the same antibiotic will not affect them.

 

Genes to resist various antibiotics are natural for bacteria to produce because the many species of bacteria war with each other for more space using these chemicals on each other.  In order to protect itself a given species of bacteria would at least have genes for resistance to the particular antibiotic it produces.  Resistance genes can also be produced by random mutation, usually through mistakes in copying the DNA during cell division.  Furthermore, bacteria can pass genes for antibiotic resistance between strains and even between species.   

 

Because antibiotics have been used so widely in medicine, there is increasing concern about developing strains of bacteria that can acquire multiple resistances to most of the antibiotics we use.  High compliance with infection control measures and a prudent and more restrictive use of antibiotics are the key measures to prevent epidemics based on bacteria with multiresistance.

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