How Bacterial Strains Become Resistant

How Bacterial Strains Become Resistant
Bacterial multiply rapidly, doubling every half hour of conditions are right. However bacteria occupy niches, and there is competition between various types of bacteria to occupy a given niche.

If a strain of bacteria has a desirable trait, it will proliferate more rapidly than a strain without that trait.

For example, bacteria that grow over a wider temperature range have an advantage over bacteria that only thrive in temperatures with little variation.

Antibiotic resistance (also called antimicrobial resistance) is an extremely desirable trait because it is advantageous in all niches.

With this kind of trait, the strain has not only a local advantage but also almost universally overwhelming advantage.

So bacterial with this trait can disseminate through many or even all niches it has exposure to.

Therefore, a treated animal, treated human, portion of the environment, or even a group environment, line an intensive care unit, daycare center or a cattle feedlot, can become one big niche instead of several niches.

Bacteria also have the ability to swap traits. Resistance to antibiotics is a specific trait that causes bacteria to make a specific protein that inactivates the antibiotic or circumvents the otherwise damaging effect of the drug.

The instructions for making specific proteins are encoded in the genes. Unfortunately, resistance genes often get encoded in genetic elements that are outside the chromosomes, or extrachromosonal.

Some extrachromosonal elements are plasmids, which are self-replicating double strands of DNA.

Some of the plasmids are able to transfer themselves to other bacterial cells. This makes the previously resistant bacteria resistant to antibiotics.
How Bacterial Strains Become Resistant