One-Up On Bacteria!

Oct 2, 2014 By Radhika, Guest Editor
Radhika's picture

If you come down with a fever or other bacterial infection, your doctor will most likely prescribe you a dose of antibiotics - drugs that prevent the growth and spread of bacteria.

While there are many antibiotics currently being used, no single antibiotic is completely successful. Scientists are constantly on the search for new ways to combat the microorganisms.

Now, researchers at MIT have found a novel way to fight bacteria: CRISPR.

The Problem With Antibiotics

Antibiotics such as penicillin and methicillin are very effective in killing the microorganisms that are harmful to us. However, increased use of these antibiotics has led to the rise of antibiotic-resistant bacteria -- or bacteria that have evolved ways to protect themselves from antibiotics.

How do bacteria develop resistance to antibiotics?

  • The antibiotic enters a person’s system and begins preventing most bacteria in the body from reproducing.
  • A few bacteria have a random mutation in their genes that allow them to reproduce in spite of the antibiotic.
  • Because all bacteria without the mutation have died, only the bacteria with the mutation survive and pass on their genes—including the genetic mutation that allowed them to survive
  • A few generations later, all bacteria carry this mutation that essentially make the antibiotic useless!

Because bacteria reproduce so quickly and acquire so many random mutations in their DNA, it is easy for them to develop antibiotic resistance. The development is consistently seen throughout history; two years after penicillin started being used, most bacteria became resistant to it.

The over-usage of antibiotics can cause another problem. In our bodies, we actually have beneficial bacteria that help us with important processes such as digesting food and fighting infections. Antibiotics cannot distinguish between the bacteria that keep us safe and the bacteria that harm us, so they end up killing all the bacteria.

What Is CRISPR?

Scientists have been looking to solve this problem of antibiotic resistance. And they found the inspiration for a solution from the bacteria itself!

Bacteria use a system called CRISPR to protect themselves against viruses. CRISPR is an enzyme that can target specific genes and cut them out of an organism’s DNA. Through CRISPR, bacteria are able to kill viruses that attempt to infect them.

Scientists were able to use the same technology to program a CRISPR to “cut out” the gene that made the bacteria resistant to antibiotics. Furthermore, it does not affect the “good” bacteria, or bacteria without resistance to antibiotics. In early studies, the CRISPR has proved to be extremely effective; it was able to increase the survival of moth larvae that were infected with harmful E. coli.

Scientists are hoping to accomplish much more than simply killing antibiotic-resistant bacteria. They theorize that CRISPR could be used to create a sort of “bacteria vaccine”. If people were given CRISPR even before the onset of a bacterial infection, their bodies could prevent antibiotic-resistant bacteria from ever forming.

Courtesy BBC, CDC.gov