Microplastics may make bacteria more resistant to antibiotics, researchers say

Bacteria exposed to microplastics can become resistant to antibiotics, a new study has found. 

Researchers from the US investigated how bacteria reacted when exposed to different concentrations of microplastics – small plastic pieces measuring less than five millimetres that are omnipresent in the environment and the human body. 

They used Escherichia coli (E. coli), a common bacteria that can have pathogenic strains and cause infections such as food poisoning.

“The plastics provide a surface that the bacteria attach to and colonise,” Neila Gross, a PhD candidate at Boston University in the US and lead author of the study, said in a statement.

When they’re on a surface, bacteria create a protective layer called a biofilm. 

The researchers then tested four common antibiotics. 

When the biofilm and microplastics were combined, the drugs didn’t work, according to the findings published in the journal Applied and Environmental Microbiology on Tuesday. 

“We found that the biofilms on microplastics, compared to other surfaces like glass, are much stronger and thicker, like a house with a ton of insulation,” Gross added.

Among the different plastics tested, “polystyrene, in particular, had the most significant impact on resistance development,” the authors wrote.

A major public health risk

Antimicrobial resistance (AMR) is considered by the World Health Organization (WHO) to be one of the top global public health threats. 

AMR makes bacteria, viruses, fungi, and parasites harder to treat and threatens human, animal, and plant health.

In 2020, more than 865,000 antibiotic resistant infections occurred across European countries, and more than 35,000 people lost their lives due to the infections.

“The fact that there are microplastics all around us, and even more so in impoverished places where sanitation may be limited, is a striking part of this observation,” said Muhammad Zaman, a professor of biomedical engineering at Boston University. 

“There is certainly a concern that this could present a higher risk in communities that are disadvantaged, and only underscores the need for more vigilance and a deeper insight into [microplastic and bacterial] interactions,” he added.

Previous research has shown that forcibly displaced populations are at an increased risk of being exposed to antimicrobial resistance due to living conditions in overcrowded camps and barriers to health systems.

Experts are calling for more research on the topic as the study took place in “controlled lab conditions,” Shilpa Chokshi, a professor at the University of Plymouth in the UK, said in a statement, adding that caution should be used when interpreting the results. 

“This was a lab study using E. coli and four antibiotics under controlled conditions, which does not fully replicate real-world complexity.  Further research is needed to assess whether these effects translate to human infections or environmental settings,” Chokshi, who didn’t take part in the study, added.