I’m talking about antibiotic resistance

What is antibiotic resistance?

Antibiotic resistance is where the bacteria you are trying to kill are resistant to the drugs you are using to kill them. Let’s say you want to eradicate this troublesome bacteria that is causing you fever and an upset stomach. You take an antibiotic (e.g. penicillin) to kill it but it just won’t go away.

This doesn’t seem that bad, though right? I mean, so what if there are a few bacteria in your system that you can’t kill but are making you sick. You’ll recover eventually, right? Wrong. Some of these antibiotic-resistant bacteria can cause dangerous infections, and lead to serious disability or even death. Not convinced? Read on.

Where did these antibiotic-resistant bacteria come from?

The Centers for Disease Control and Prevention (CDC) estimates that more than two million people in the US alone are sickened every year with antibiotic-resistant infections. At least 23,000 of them die as a result (2017 CDC report ‘Antibiotic Resistance Threats‘). But where did these dangerous, resistant bacteria come from?

Mechanism: Evolution and the safety in numbers
Bacteria evolve very rapidly to environmental stressors like antibiotics, and this process is fascinating: Upon exposure to stressors, many bacteria will rapidly dividing where they replicate their DNA with a lot of random mistakes (aka mutations). Sounds counterintuitive right? But bacteria, being unicellular, have safety in numbers. There’s so many of them (did you know that one gram of soil has 10 billion bacteria in it?) that they can afford to lose a lot more. When exposed to stressors like antibiotics, they randomly (and rapidly) mutate and most of the new highly-mutated cells produced die – either from the antibiotic or because they had mutations that made them defective. But every once in a while (and I mean once in a few billion or trillion), a mutation allows the bacterium to break down the antibiotic stressor. It’s like playing the lottery except you have 10 billion tickets instead of one. Now, with all the competition gone, this single resistant bacterium can rapidly divide and produce many, many more resistant progeny. Survival of the fittest at its best.

But here’s the catch – we could make this process really difficult for bacteria. We have strong antibiotics that will kill all the bacteria so fast that they can’t evolve and become resistant. So what’s the problem? Why do we still have antibiotic-resistant bacteria?
There are two big causes: (1) abuse/misuse in treating illnesses in humans, (2) abuse/misuse in the meat and dairy industry.

Antibiotic misuse in treating human illnesses

The biggest cause of this rise of resistant bacteria is the abuse and misuse of antibiotics in the treatment of illness. Look at the schematic below for how antibiotic-resistant infections are established.

Antibiotic misuse in the meat and dairy industry

Another place where gross misuse of antibiotics occurs is in the meat industry. According to a Food and Drug Administration (FDA) report, 80% of US antibiotics are used for animals. Animals are given antibiotics for growth promotion and increased feed efficiency. The bacteria associated with these animals (e.g. in the gut of cows or chickens) are exposed to low doses of antibiotics over a long period of time, allowing them to become resistant. These resistant bacteria can then spread to people via (1) handling or consumption of raw/under-cooked meat, (2) contact with animal stool (directly or through water run-off), (3) from touching/ caring for animals. In the future, if you ever see any meat/ dairy products advertised as “Raised without antibiotics” or “No antibiotics administered”, please choose those over others. You will be making a healthier, safer choice for you and your family. In fact, Forbes Magazine has put together a great infographic highlighting this:

In the future, if you ever see any meat/ dairy products advertised as “Raised without antibiotics” or “No antibiotics administered”, please choose those over others. You will be making a healthier, safer choice for you and your family. In fact, Forbes Magazine has put together a great infographic highlighting this:

What exactly is at risk here?

To put it lightly, EVERYTHING is at risk here. To fully comprehend the danger, let’s do a thought experiment. There is a bacterial species (let’s call it Y2K) that is highly pathogenic to humans. It is so pathogenic that a Y2K infection lasting just 10 days can be fatal. After doctors try treating Y2K infections, they find that it is resistant to all our clinically-used antibiotics. It’s as if it doesn’t even recognize you’re trying to kill it. Person after person gets infected with Y2K and nobody knows what to do. In today’s highly-interconnected society, the infection spreads from one continent to the other. People are dropping like flies. In just a few short months, more than half the earth’s population is wiped out. Scared yet? This possibility is very real and scenarios seen in movies like Outbreak (1995) and games like Pandemic might not be very far from the truth.

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Is there anything I can do to stop this?

The CDC prescribes 4 things that we can all do about the antibiotic resistance threat.
1. Prevent infections, thereby preventing the spread of resistance
2. Tracking
3. Improve antibiotic prescribing and use, aka “STEWARDSHIP“
4. Developing new drugs and diagnostics

It’s the 3rd point above that really applies to us all. Here’s how you can be a good steward:
(1) Don’t take antibiotics unless absolutely necessary. They really do harm your body deeply by disrupting your healthy, essential microbiome.
(2) If you are prescribed antibiotics, complete the course of the antibiotics. I’ve seen this so many times – by Day 2 of antibiotics, you’re starting to feel better and think “Oh, I don’t need antibiotics anymore! Yay!” But that’s irresponsible. To really kill the last few pathogenic bacteria, you need to complete your course. If you don’t kill them all, they might just come back to kill you.

The biggest, baddest bacteria in the world

Humans love drama. We all want the inside scoop and learn about the extreme, the dangerous, and the scary. So I thought I’d write a little section on what we’re up against in this battle against the bugs.

Carbapenem-resistant enterobacteriaceae (CRE)

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Carbapenems are our strongest, most effective group of antibiotics. And CRE bacteria are resistant to them. This group includes Salmonella, E. coli, Klebsiella and is found in many clinical settings. It is estimated that 50% of these CRE infections are fatal.

Methicillin-Resistant Staphylococcus aureus (MRSA)

This is the archetypal “superbug”. Staphylococcus aureus exists peacefully in some parts of the body but can turn pathogenic if it gets in deeper (e.g. through wounds). MRSA is now resistant to all clinical antibiotics except our last resort antibiotics. Infections often occur in nosocomial (i.e. hospital) settings.

Acinetobacter baumannii

Best for the last? Maybe. Strains of Acinetobacter baumannii have been discovered that are resistant to even our last resort antibiotics. Discovery of antibiotics against A. baumannii is critical. This bacterium mostly affects people with compromised immune systems and infections most often occur in nosocomial settings. Infections result in pneumonia, wound infections, and sepsis. How is this bacterium resistant to all our antibiotics? Turns out these guys have a lot of cellular machinery to pick up or steal pieces of DNA from other species and use them if they are beneficial to it. Yikes.

Summary

• The threat of bacterial antibiotic resistance is real, urgent, and scary.
• Bacteria are able to become resistant to antibiotics through rapid evolution in the form of random, error prone DNA replication that introduces mutations all over the bacterium’s genome.
• You can do your part to prevent antibiotic resistance from getting worse – take antibiotics only when you need to, and follow prescribed courses all the way to the end.

References:
– CDC page on antibiotic resistance (aka antimicrobial resistance) https://www.cdc.gov/drugresistance/index.html
– CDC guidelines on good stewardship
https://www.cdc.gov/antibiotic-use/stewardship-report/pdf/stewardship-report.pdf
– Forbes magazine – antibiotics use in the meat industry
https://blogs-images.forbes.com/bethhoffman/files/2013/03/Antibiotics_in_Meat.jpg
– “Molecular mechanisms of antibiotic resistance” Blair, et al. Nature Reviews Microbiology volume 13, pages 42–51 (2015)