Microplastics and antibiotic resistance — a furtive threat
Microplastics, microbes and antibiotic resistance
It is about time to address an underestimated threat that is lurking: the role of microplastics in the rise and spread of antibiotic resistance. What may not seem to be related at first sight is starting to become a real threat to our health.
Research shows that plastic particles — independent of size — is probably the new place to be as a successful microbe. No matter if on land or in water — scientists did see that microplastic and co harbours the who-is-who of the microbial community.
The population of plastic particles is closely related to its superficial structure. However, most of the bacterial communities living on plastics have one thing in common: a good neighbourhood (unlike the one some of us may have experienced).
In many cases, microorganisms share the plastic particles in form of biofilms — the ultimate form of a great neighbourhood. That however is potentially making microplastics an even bigger threat than they already are.
Microplastics — a source for antibiotic resistance
In principle, a biofilm is a microbial ecosystem and consists of a protective coating (a slimy layer build from extracellular fluids). Therewithin, bacteria, fungi, algae, and every other microorganism you can think of (yes, also pathogens!) enjoys live in a save “bubble”. Actually, up to 1 trillion microbial cells can live within this safe haven!
(Off-topic: the world record for counting to the highest number (loud!) is 1 million- held by Jeremy Harper. It took him 3 months where he counted for 16 hours straight each day (1)! Counting from 1 to 1 trillion would take around 1 million times as long. Before you consider trying out yourself. It would take you 243835 years! Mental breakdowns and miscounting are not included in this calculation!)
Back to microplastics and antibiotic resistance. The biggest threat of biofilm formations on plastic particles? On one hand, the protective coating does exactly what it’s meant to be: it protects the microorganisms living within it from external threats. However, what we also need to consider is, that the numbers mentioned before mean an unbelievable big amount of microbes is living together on a very small scale. Therefore, genetic exchange between different individuals (for example through conjugation) is much more likely than outside of this bubble. This way, antibiotic resistance genes can easily spread within the biofilm. I told you — great neighborhood!
Microplastics and their role in spreading antibiotic resistance
To recap: plastics of all size enhance the formation of microbial biofilms, which again enhance the genetic exchange between microbes. This also contains sharing their respective antibiotic-resistance genes. Furthermore, the worldwide spread of plastic particles is adding to this problem. Even the most pristine areas like our poles are also reported to be contaminated with plastics and it is to assume, that antibiotic resistance microbes are carried alongside. This phenomenon has actually been reported already for the antarctic area (Laganá et al. 2019).
An increased selective pressure, the disturbance of existing ecosystems, and the transfer of resistance genes to other bacterial strains outside of the biofilm are the consistent consequence and it is only a matter of time until this whole thing is dropping back to us.
To date, ‘PlasticsEurope’ also reported, that humans are consuming microplastic particles day by day (especially through seafood) (2). Biofilms and their respective (potentially antibiotic-resistant) microbes aren’t really making things better, do they?
However, it is still hard to tell where we are heading as science is still in its infancy regarding microplastics and antibiotic resistance. Anyway, it is already clear that the threat of microplastics adding to the antibiotic-resistance crisis is real and needs to be considered when we are talking about the global spread of plastics in nature.
References
(1) https://www.guinnessworldrecords.com/world-records/100483-highest-number-counted-out-loud
(2) https://plasticseurope.org/wp-content/uploads/2022/10/PE-PLASTICS-THE-FACTS_V7-Tue_19-10–1.pdf
