Microplastics, the tiny plastic fragments polluting the environment, may be playing a significant role in the spread of antibiotic-resistant bacteria, a new study suggests.
Researchers at Boston University found that these microscopic particles provide an ideal surface for bacterial biofilms—slimy protective layers that allow bacteria to thrive and resist antibiotics.
Bacteria naturally form biofilms as a defense mechanism, creating a sticky, three-dimensional structure from their own waste. This protective layer shields them from external threats, including antibiotics. While biofilms can develop on various surfaces, plastics appear to be particularly well-suited for their formation, attracting bacteria more effectively than materials like glass, according to the study.
“Microplastics are like rafts—a bacteria on its own might not be able to swim down a river, but riding in its biofilm on a tiny bit of plastic, it can be disseminated into many different environments,” explained Neila Gross, the study’s lead author and a doctoral student in materials science and engineering at Boston University.
To test the effects of microplastics on antibiotic resistance, researchers grew biofilms of Escherichia coli (E. coli) on both microplastics and glass spheres. They then exposed these biofilms to four commonly used antibiotics: ciprofloxacin, doxycycline, fluoroquinolone, and ampicillin.
The results showed that E. coli biofilms grown on microplastics developed much faster, became larger, and exhibited significantly higher antibiotic resistance than those formed on glass. Even more concerning, when the bacteria were later removed from the microplastics, they retained their ability to create stronger biofilms.
“These bacteria were not only resistant to antibiotics, but they were also better at creating biofilm,” Gross said. “For microplastics to facilitate bacteria to be these faster, better biofilm formers is quite concerning.”
The study’s findings suggest that microplastics may contribute to the spread of drug-resistant bacteria in various environments. Senior study author Muhammad Zaman, a professor of biomedical engineering and global health, emphasized the broad impact of this phenomenon:
“We found the link between microplastics and how they lead to antimicrobial resistance is both real and not limited to a single antibiotic,” Zaman said. “It’s broad, impacting many commonly used antibiotics, which makes it really, really concerning.”
The presence of microplastics in high-density areas with poor sanitation, such as refugee settlements, could exacerbate bacterial infections, the researchers warned. They suggested monitoring such environments for microplastic-related antibiotic-resistant bacteria and viruses.
While the study provides strong evidence of a connection between microplastics and antibiotic resistance, experts emphasize the need for further research. Shilpa Chokshi, a professor of environmental hepatology at the University of Plymouth, noted that the study was conducted under controlled laboratory conditions and may not fully replicate real-world complexity.
“This was a lab study using E. coli and four antibiotics under controlled conditions, which does not fully replicate real-world complexity,” Chokshi said. “Further research is needed to assess whether these effects translate to human infections or environmental settings.”
