The dangers of bacteria’s secret weapons

Researcher Theresa Wagner at UiT The Arctic University of Norway with decent growth of Staphylococcus Aureus bacteria. Credits: Jan Fredrik Frantzen, UiT The Arctic University of Norway

Did you know that bacteria can hide their antimicrobial resistance? Like storing military defense equipment without revealing it to the enemy, bacteria can mask their ability to resist antimicrobials. This hidden antimicrobial resistance can fly under the radar and cause treatment failure in patients.

A recent study published by researchers at UiT The Arctic University of Norway sheds light on this “hidden resistance”. The researchers describe that this phenomenon is often so rare that you cannot detect it through traditional testing methods, such as growing the bacteria in a petri dish. However, when bacteria are exposed to antimicrobial drugs during treatment, they can activate their hidden defense equipment, rendering the patient’s treatment ineffective.

In addition, bacteria can share their antimicrobial abilities with other bacteria, leading to the emergence of drug-resistant strains that threaten public health. It’s like they’re conspiring against us in a secret brotherhood.

Such bacteria are not just a scary idea to think about. In fact they continue to appear in many places around the world.

The secret of bacteria

Detecting bacteria carrying hidden weapons can be a daunting task for even the most skilled of lab technicians. Only one in a million bacteria carry these hidden weapons, which is like looking for a needle in a haystack.

On the other hand, we usually use “only” ten thousand bacteria to do a test of observable characteristics, a so-called phenotypic test in the laboratory, where we grow the bacteria in a Petri dish. But we’d have to use a million bacteria to find the one with the secret super weapon.

You might think it’s not such a big deal when so few bacteria carry hidden weapons. However, when you have an infection, the number of bacteria multiplies rapidly and soon there are more than a billion bacteria.

At that point, several bacteria have hidden antimicrobial weapons. And yet, they still have a trick up their sleeveā€¦

The dangers of bacteria's secret weapons

Colonies of enterococci in a petri dish. One in a million of the bacteria on that plate will have the blueprints for antimicrobial resistance hidden in their genes. Credits: Jan Fredrik Frantzen, UiT The Arctic University of Norway

Whispering in the lane

When bacteria notice that they are threatened by antimicrobials, they pull out their secret weapons and destroy the drug’s effect. But they can also share their program of how to make these weapons with other bacteria. They make several copies of the blueprint and share it with their partners around them.

The result is that even more bacteria can suddenly be equipped with secret weapons. And the patient does not recover from the infection.

DNA – the secret storage

What can we do to detect and prevent the spread of such rogue and dangerous bacteria? The most important thing of course is that you, as the reader of this article, use antimicrobials only when you need them. Second, in the laboratory we can combine traditional methods of observable traits with methods that examine the genetic information of bacteria.

With methods like PCR and genomic sequencing, we can look into the innermost secrets of bacteria. More specifically, we can take a look at their nucleic acids.

At the gene level, even bacteria can no longer hide their secret weapons designs.

Double test

In Denmark and Canada, strains of enterococci with latent resistance have been able to spread rapidly and cause outbreaks of disease in hospitals. In Norway and Sweden, early detection and more widespread use of genetic analysis of Enterococcus DNA has so far prevented the spread of latently resistant bacteria.

In the coming years, we expect to find even more hidden resistance in bacteria. This means that hospitals and research communities need to be vigilant and update methods to identify bacteria’s secret weapons and designs. Since we can only look for bacterial weapons that we already know about, we must continue to search for other, and perhaps completely different, defenses that bacteria have hidden that we still don’t know about.

The study is published in Journal of Antimicrobial Chemotherapy.

More information:
Theresa Maria Wagner et al, Transiently silent acquired antimicrobial resistance: an emerging challenge in susceptibility testing, Journal of Antimicrobial Chemotherapy (2023). DOI: 10.1093/jac/dkad024

Provided by UiT The Arctic University of Norway

Reference: The Perils of Bacteria’s Secret Weapons (2023, March 10) Retrieved March 12, 2023, from

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