Rising Dawn of Superbugs

It perhaps lies within the microscopical feature of these creatures that some turned out so malicious and pathogenic whereas others play an important role in what makes you, well… you.

They’re more often deemed as “germs”’ that can invade our bodies and make us sick, but a great deal of them actually serve many purposes such as maintaining the properties of the soil and atmosphere, helping decompose complex substances into basic nutrients for plants, as well as humans, forming the so called human microbiome. They also help synthesize vitamins or even protect us against exogenous threats, but not the intergalactic type just yet.

This is the first article from a series with cool stuff about bacteria that I prepared and the main talk will focus on the nasty aspects of these inconspicuous microorganisms that never cease to amaze us, as they pursue their continuous and tangled ways for survival.

Bacteri-AHH!

Bacteria-Neutron-Dev

First let’s get a close-up on what a bacterium is.

It’s a single cell microorganism that’s found pretty much everywhere, from your sandwich, dog and friends to unfriendly places that lack oxygen and light. They are in general more resistant than viruses which always need a host to begin with because they don’t have the supplies required to sustain themselves.

But bacteria do and they can thrive pretty much everywhere.

Frederick Griffith was the first to propose, through his experiment in 1928, that there was a way bacteria could transfer material to another organism that was not its offspring, and many studies followed.

Frederick Griffith experiment

Griffith’s experiment discovering the “transforming principle” in pneumococcus bacteria. [Source: Wikipedia]

In the aftermath of World War II, infrastructure and population’s morale were not the only things that suffered, as many people contracted pneumonia. That compelled some bright minds around the world to find an imperative cure.

Griffith used two strains of pneumococcus bacteria to infect mice, one that was virulent , thus triggering the disease, and a nonvirulent or innocuous one, that lacked the capsule the virulent one covered itself in, which basically served as an invisibility cloak to our immune system.
Having been exposed, the immune system of the mouse protected the organism and the animal lived, whereas in the other case, it didn’t.

A while later, Fred Neufeld, a german bacteriologist, decided to heat up the virulent strain and then insert the remnants in a mice, once mixed with the nonvirulent strain and the second time on their own (different mice, of course).
As the heat killed most of the bacteria, the remains alone were not enough to harm the mice.

But surprisingly enough, combined with the nonvirulent bacteria, they managed to kill the host because the nonvirulent strain took up some of the DNA left from the heating process, including the genes needed to synthesize the capsule.

So through this process that was called transformation, some genes were passed on in such a manner that it allowed the nonvirulent strain to grow a capsule and cheat the immune reaction resulting in the death of the host.

Transformation is one of the three processes for horizontal gene transfer, along with conjugation and transduction.

The former implies the transfer of genetic material between bacterial cells via direct contact whereas the latter requires a vector, more specifically some little viruses than can infect bacteria, called bacteriophages.

And yes, bacteria can also get sick but you probably didn’t know that because they don’t whine about it as much we do.

The process called horizontal gene transfer enables a bacteria to adapt to their environment much more rapidly, by acquiring some DNA sequences from another bacterium in a single transfer and it’s the main mechanism that leads to antibiotic resistance.

We are born with a nice set of genes that, besides more complicated and useful things, also make us have blue eyes, for example, even if we want it or not.

blue-eye-neutron-dev

And this is one of the aspects we cannot change because they are encrypted in our genetic code.

We get those genes from our parents and we’re stuck with them all our lives, through vertical transmission of DNA, but bacteria can, at some point, just steal some DNA around it and take on its properties from that point on.

Let’s say a bacteria that is resistant to heat and could live in boiling water died and another cunning one that happened to pass by at that moment decides to grab some genes and now is also resistant to heat.

Some scientists have called it “the funeral grab“.

It’s like you wanted to have green eyes and you just went to a green-eyed person’s funeral for that, but sadly this also works for antibiotics and instead a bacteria got resistant to tetracyclin.

As one of my favourite persons on YouTube, Trace Dominguez once said :

Superbugs are becoming more super and antibiotics less anti” — so we need to take these gruesome little creatures more seriously as they keep outsmarting our technology.

Earlier this year, the World Health Organization has released a list with the ranking of the most treacherous bacteria and calls for the ramping up of development of new antibiotics, targeting these soon-to-be-incurable diseases.

Dr. Marie-Paule Kieny, the WHO’s assistant director-general for health systems and innovation, stated that “Antibiotic resistance is growing and we are running out of treatment options. If we leave it to market forces alone, the new antibiotics we most urgently need are not going to be developed in time“.

You can find the full list here.

Kieny said “the 12 bacteria featured on the priority list were chosen based on the level of drug resistance that already exists for each, the numbers of deaths they cause, the frequency with which people become infected with them outside of hospitals, and the burden these infections place on health care systems.”

In case you missed the latest studies on the topic, there’s a serious concern on how superbugs grow resistance faster and faster as the last-line antibiotics are failing.

And the long-term consequences in the foreseeable future could be pretty big.

A woman from the US died this year because she contracted an illness caused by a MDRB (multidrug-resistant-bacteria) which was impassive to each and every drug on the US market.

It’s an insidious process that some bacteria undergo, but it’s not as striking as a growing forest fire and most certainly people are not simply falling like logs on the street because of it, more rather subtly fading away in a hospital bed.

A team of scientists has paired up in a lab at a Harvard Medical School to study antibiotic resistance and to also help us visualize the awe-inspiring evolution of the bacteria growing in such conditions by making a giant Petri plate they called MEGA (Microbial Evolution and Growth Arena).

It took 11 days for the bacteria to develop minimal mutations in order to keep growing and resist to all the antibiotics that were tested.

You can see the colonies growing in bursting waves in the video below.

The means by which a bug can become so  ‘super’  derive out of random changes in DNA that enable them to build up a better outer shield to prevent the antibiotic from passing through the membrane, or design ways to combat it in the cytoplasm or form pores to get it back out.

Some smart bacteria can even alter or change the proteins on their surface to mislead the antibiotic into recognizing the target spot it was supposed to bind to.

This is called Antigen variation.

Another mischievous method bacteria from certain species use  is changing plasmids, or small lumps of circular DNA, with another bacteria friend that further teaches it to become intrinsically resistant to a certain drug.

This is called conjugation.

Plasmids basically help bacteria resist to continuous stress – too bad students aren’t that advanced as a species, huh?

Despite using an awful lot of energy for replicating independently of the bacterial nucleus, plasmids make themselves essential to the host in certain occasions.

If a bacterium undergoes a rather stressful period, its plasmids can enable it to become resistant to some of the conditions (or antibiotics).

Or if some harsh conditions deprive the bacteria of its nutrients, the plasmids can help it digest other substances in order for the host to survive. In this way, plasmids make sure that they are kept around.

But there are also some sneaky ways that can ensure a plasmid’s spot within the cell. Some plasmids have a gene that encodes a long-lived poison and a second one that encodes a short-lived antidote for that poison.

In this way, the cell is basically kept hostage and must fit the needs of the plasmid. This deal usually ends with the death of the host as soon as it loses the plasmid, along with the supplies of the remaining antidote.

We do fight back

Keep in mind that despite all this ominous means superbugs behave and manage to be harmful for their well-being, researchers all around the globe put strenuous effort into developing new cures and technologies to overcome them.

After all, evolution works for all of us, throwing at a wall various mutations to see what sticks, whereas technology is aimed evolution with the further goal of taking the human race to the next level.

Anca

Anca

Science lover, stargazer, professional sleeper.
Anca

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