Dr. Dave Science

There has been a lot talk in the news about MRSA, which stands for Methicillin-Resistant Staphylococcus Aureus.

Scientists often call MRSA a “superbug” because it no longer can be killed by a certain kinds of antibiotics related to penicillin.

How is it that bacteria become “superbugs?”

Bacteria are tiny, one-celled organisms that come in many shapes and sizes. All bacteria use DNA as the blueprint of life and have tools (called enzymes) to copy itself when ample nutrients are present.

Before copies can be made, a bacterium has to duplicate its DNA. An enzyme called DNA Polymerase (the horseshoe shaped object shown in green in the picture above) accomplishes this task. This enzyme is found in bacteria, insects, plants, animals, and even humans!

When making copies of DNA, most DNA Polymerases can proofread the blueprint to check for errors. Human and plant Polymerases are very good at finding errors, but some bacterial Polymerases are not. If an error does occur in the blueprint, scientists call this a mutation.

Mutants!

When people hear the word “mutant” they think of X-men or the Teenage Mutant Ninja Turtles. Although this is science fiction, Hollywood has shown that there are good mutants and bad mutants. The same applies to bacteria.

For example, scientists have engineered good mutant bacteria that can make insulin, a hormone used by diabetics to control blood sugar levels.

An example of a bad mutant bacterium is MRSA, which we talked about above.

More About Mutations

The DNA blueprint holds the master plans for all the machinery required for a cell to function properly. If there is a mutation in the blueprint, there is a chance that a cell’s machinery of life will be altered, and it can result in one of three possible outcomes:

1. The altered machinery continues to function normally.

2. The altered machinery is faulty and can cause bacterial death.

3. The altered machinery is enhanced and it helps the bacteria survive harsh conditions.

Survival of the Fittest!

Harsh conditions could mean a variety of things to bacteria, from low nutrient levels to the presence of antibiotics.

We already know that antibiotics can kill bacteria, but what happens if a mutation helps the bacteria survive? Scientists call this resistance.

Bacterial resistance to antibiotics is a very scary thing. Diseases that were once curable are now becoming a challenge to control.

The world’s best scientists are working hard to discover new kinds of antibiotics. Hopefully there will be breakthroughs that will lead to new medicines that will control the spread of these lethal bacteria.

-Dr. Dave