Science, Now + Beyond

ASK A SCIENTIST: What are superbugs?

If you think taking an antibiotic for your cold has no impact outside of your own body, think again.

You may have heard the term “superbugs” in some media headlines. You’ve also probably been prescribed an antibiotic by a doctor before. Have you ever wondered why you haven’t been prescribed one for a cold?

Don’t be fooled: “superbugs” aren’t some kind of superhero insects. They’re the villainous faces behind a global health crisis causing 700,000 deaths per year. What are “superbugs”, and why sould we be worried about them?

The difference between bacteria and viruses

Bacteria are unicellular organisms that cause many of the diseases animals (including humans) can get through infection. The type of infection depends on how they enter our bodies. To name a few: Staphylococcus aureus bacteria often enter through skin and cause skin infections, Streptococcus pneumoniae can enter through our airways and cause pneumonia, Escherichia coli can enter through our urethras and cause UTIs, and Chlamydia trachomatis can enter through our reproductive tracts to cause an STI. Some of these bacteria have multiple sources of entry, causing various other diseases.

Viruses, meanwhile, are infectious agents that exist somewhere in the grey area between living and non-living. They don’t meet our current definition of “life”: they cannot replicate outside of a host cell. They have very different properties from the ones that make up the cells of bacteria. Rhinovirus is the most prevalent virus genus responsible for the common cold, while influenza virus causes flu, and norovirus causes food poisoning.

How do antibiotics work?

There are many classes of antibiotics, and their distinctions are based on where in the bacterial cell they are attacking or how they are attacking. One drug most familiar to us — penicillin — works by inhibiting an enzyme in bacteria that helps create the bacterial cell wall. This stops the bacteria from being formed. Another antibiotic, ciprofloxacin, kills an infection by interfering with bacterial DNA replication and transcription. The drug erythromycin does this through a third mechanism: by inhibiting bacterial protein synthesis.

Because viruses do not have those properties being targeted by antibiotics, those drugs will not effectively kill them. Some viruses have antiviral drugs that work against them, like acyclovir for herpes simplex virus, but others have no treatment whatsoever, like the common cold.

So, what are “superbugs”?

Just like us humans, bacteria undergo genetic mutations, which make each one of them a little bit unique within their species. Perhaps a mutation causes a bacterium in the bunch to produce an extra, powerful enzyme.

Now, let’s say this population of bacteria lives in a human’s body and is being treated with an antibiotic for five days. Each day the person takes the drug, they kill more and more bacteria, until (hopefully) it’s gone. But if any were left, what qualities might they have?

Remember “survival of the fittest”? The weaker bacteria are killed first, while the strongest survive. The survivors could be those organisms with the extra, powerful enzyme. These bacteria go on to replicate and pass their drug-resistant genetic material on to generations of billions of microorganisms, and the new norm for the population’s traits changes. Voilà, natural selection in action.

This really happened! Penicillin was the earliest antibiotic discovered by modern medicine. Decades after it was put into practice, scientists started to find an enzyme called penicillinase in the bacteria Staphylococcus aureus. This enzyme deactivated the drug penicillin. So, drug researchers developed clavulanic acid to specifically target that bacterial enzyme. It was added to penicillin-like drugs to be able to fight these stronger bacteria, and we still use Augmentin (amoxicillin + clavulanic acid) for ear infections.

An antibiotic can also kill off good bacteria which serve important purposes in our bodies. This promotes an environment ripe for resistant bacterial infections to reproduce unhindered.

Developing Drug-Resistant Infections

Penicillinase hasn’t been modern medicine’s only obstacle. Over the years, our response has been to develop new antibiotics that work in novel ways. But bacteria continue to find more ways to trick us. MRSA (Methcillin Resistant Staphylococcus Aureus) is a common, fatal threat in hospitals. The CDC recently reported that there was a fourfold increase last year in resistance towards one of the drugs used to treat gonorrhea. And multi-drug resistant Acinetobacter baumanii, already being treated with one of the strongest antibiotics on the market, has growing resistance to this last-resort drug.

Drug development is a grueling process that can’t keep up with superbug evolution. Soon, there may not be any big guns left.

What can be done about “superbugs”?

To tackle to the problem, we must correctly identify the causes.

Healthcare workers can help fight the problem of resistance by properly educating patients on antibiotic use, only prescribing antibiotics when needed, and prescribing the least powerful antibiotic effective for a treatment or immediately downgrading to a lower spectrum antibiotic when cultures come back. They should also practice proper hand hygiene, especially in hospitals where resistant bacteria spread rampantly.

All of us can help tackle resistance by only using antibiotics prescribed by our doctor, finishing the full prescription even when symptoms are gone, and not stockpiling or sharing antibiotics. For the virus-caused common cold, drink lots of fluids and seek symptom relief through over-the-counter drugs only. Prevention of infection in the first place is ideal, which means practicing hand hygiene as well as using barrier protection for STIs. Factory farms pump antibiotics into animals whether they’re sick or not, and when the livestock develop drug resistant infections they get passed down to us through unhygienic food handling. So, we should wash meat and produce, and try to buy organic when possible. And finally, stay informed: You can read the CDC’s report about the current biggest global infectious threats here.

Our individual antibiotic use doesn’t exist in a vacuum. But our collective action can help turn global health around for the better.