Staphylococcus aureus. A devious little bugger and a master of improvisation.(Illustration: Stephen Dela Ahator / DALL-E)
This bacterium outsmarts our defences, but we are on its heals
POPULAR SCIENCE: Meet Staphylococcus aureus, the ultimate microscopic escape artist that invades, adapts, tricks, and thrives within our bodies.
StephenAhatorPostdoc researcher at UiT The Arctic University of Norway and CANS – Centre for New antibacterial Strategies
Published
As part of the larger global crisis of antimicrobial
resistance (AMR), the bacterium Staphylococcus
aureus represents a formidable challenge.
You might have heard about MRSA? This is the version
that is resistant to the antibiotic Methicillin, and it is pushing modern
medicine to its limits.
Infections with Staphylococcus
aureus range from mild skin irritations to serious life-threatening
diseases like pneumonia and bloodstream infections. This places it at center stage of the ongoing battle between microbes and medicine.
The invisible battle inside your body
Whether it’s dodging your immune system’s attacks or
hijacking your cells’ energy, this microbe has evolved survival strategies that
challenge our immune system and even our best antibiotics. The result is a
brutal match between two hardcore players chasing each other inside your body.
Annonse
On one side of this war is Staphylococcus aureus. On the other side is
your strong immune system, constantly defending you.
But how does this tiny invader manage to outsmart such
a powerful defence network as our immune system?
The bacteria’s strategy: Sensors, metabolism,
and stealth
Now, our research has uncovered both the bacterium’s
secret playbook and its weaknesses. We can exploit these findings to turn the
tide in this microbial arms race.
The skin cells, acting as the first line of defence, form a protective fortress against invading bacteria that can cause disease. Macrophages, the immune system’s warrior cells, are our second line of defence. They work by actively engulfing and neutralising the invading bacteria. Meanwhile, the bacteria counterattack with toxins and evasion strategies, illustrating the ongoing tug-of-war between host defences and microbial invaders.(Illustration: Stephen Dela Ahator)
Our research discovered that Staphylococcus aureus is
equipped with a 'radar system' called a two-component system (TCS).
This clever system detects threats and helps the microbe adapt, attack
cells, and survive under tough conditions.
If we disrupt this two-component
system, the bacterium becomes weaker and less harmful. Now this presents us
with an exciting path for new treatments.
When it is inside immune cells like macrophages, on the
other hand, the bacterium focuses on survival and resists attacks designed to
destroy it.
Meanwhile, in skin cells, Staphylococcus
aureus avoids detection by disabling natural antibiotics and
manipulating the body’s own energy molecules, to fuel its survival.
But Staphylococcus
aureus doesn’t stop there. It’s also a metabolic shape-shifter and
capable of adapting its energy use based on the type of cell it invades. It is
like an electric car switching to petrol if there are no charging stations
around, but there is a petrol station around the corner.
This dual attack strategy makes it a formidable
opponent!
Your body’s defences: Your skin, macrophages, and food shortage
While Staphylococcus
aureus is remarkably crafty in its attempts to evade the immune
system, your body is anything but defenceless.
Your skin, the largest organ in your body, serves as
the first and most robust line of defence. At its frontline are keratinocytes. They
are specialised cells that form a tough physical barrier.
Keratinocytes produce
antimicrobial peptides,
which are natural antibiotics that puncture the bacteria’s membranes. This creates
a hostile environment for infectious agents like Staphylococcus aureus.
Annonse
Beyond the physical barriers, you have macrophages that are the
warrior cells of your immune system. They engulf invading bacteria and release
toxic chemicals to destroy them. Macrophages also wage a more subtle battle by
cutting off the bacteria’s access to iron, a vital nutrient for bacterial
growth.
The counterattack: Bacterial survival
strategies
Where macrophages are your body’s own warriors, Staphylococcus aureus is
the ultimate survivalist and can counteract our immune responses. Staphylococcus aureus fights
back with systems for scavenging iron where it can find it. It effectively
steals iron from host proteins in order to continue its reproduction.
Stephen Dela Ahator, researcher at UiT The Arctic University of Norway and CANS – Centre for New Antibacterial Strategies.(Photo: Jan Fredrik Frantzen / UiT The Arctic University of Norway)
Even more sinister is its ability to manipulate the
immune system’s macrophages into a chilling and ill-fated response. Faced with
bacterial dominance, some macrophages initiate a kamikaze-like defence
in the form of programmed cell death. It is intended to contain the threat from the
bacterium, but at the cost of the immune cell’s life.
It literally forces the immune cell to kill itself in
a desperate last stand.
Why it matters to you
Now, this story is not just about
understanding a single bacterium. It’s about arming ourselves with better tools
in the fight against antibiotic resistance. The insights from this research
pave the way for new treatments that do not rely on overused antibiotics. This
in turn reduces the risk of bacteria becoming drug-resistant.
By targeting the bacteria’s control
systems, or boosting the natural defences of our cells, we could develop
therapies that make infections easier to treat.
The bigger picture: AMR and Staphylococcus aureus
In the grand scheme of infectious diseases, Staphylococcus aureus
stands out not only because of its ability to outwit the immune system. It is
also important because of its rising resistance to antibiotics.
MRSA, for example, has become symbolic of the global
antimicrobial resistance crisis. These strains are increasingly difficult to
treat, and they are placing a growing burden on healthcare systems worldwide.
The AMR crisis that we are facing underlines the
importance of understanding the interactions between us the hosts, and infectious
microorganisms.
By deciphering how Staphylococcus
aureus slips through our immune responses, by the use of toxin
production, biofilm formation, or metabolic adaptation, we hope to develop new
therapies that can tip the scales back in favour of the immune system.
The future of modern medicine and the treatment of
infections depends on it.
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