New research has found that bacteria exposed to microplastics became resistant to multiple types of antibiotics commonly used to treat infections.
The researchers have said that this is especially concerning for people in high-density, impoverished areas like refugee settlements, where discarded plastic piles up and bacterial infections spread easily.
Muhammad Zaman is a Boston University (BU) College of Engineering professor of biomedical engineering who studies antimicrobial resistance and refugee and migrant health.
The researcher said: “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.
“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.”
It’s estimated that there are 4.95 million deaths associated with antimicrobial-resistant infections each year.
Bacteria become resistant to antibiotics for many different reasons, including the misuse and overprescribing of medications, but a huge factor that fuels resistance is the microenvironment—the immediate surroundings of a microbe—where bacteria and viruses replicate.
In the Zaman Laboratory at BU, researchers rigorously tested how a common bacteria, Escherichia coli (E. coli), reacted to being in a closed environment with microplastics.
Neila Gross (ENG’27) is a BU PhD candidate in materials science and engineering and lead author of the study.
Gross said: “The plastics provide a surface that the bacteria attach to and colonise.”
Once attached to any surface, bacteria create a biofilm—a sticky substance that acts like a shield, protecting the bacteria from invaders and keeping them affixed securely.
Even though bacteria can grow biofilms on any surface, Gross observed that the microplastic supercharged the bacterial biofilms so much that when antibiotics were added to the mix, the medicine was unable to penetrate the shield.
Gross said: “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.
“It was staggering to see.”
The rate of antibiotic resistance on the microplastic was so high compared to other materials, that she performed the experiments multiple times, testing different combinations of antibiotics and types of plastic material.
Each time, the results remained consistent.
Zaman said: “We’re demonstrating that the presence of plastics is doing a whole lot more than just providing a surface for the bacteria to stick—they are actually leading to the development of resistant organisms.”
Zaman directs BU’s Center on Forced Displacement, which has a mission to improve the lives of displaced people around the world.
Past research has found that refugees, asylum seekers, and forcibly displaced populations are at an increased risk of contracting drug-resistant infections, due to living in overcrowded camps and having heightened barriers to receiving healthcare.
Zaman said: “Historically, people have associated antibiotic resistance with patient behavior, like not taking antibiotics as prescribed.
“But there is nothing a person has done to be forced to live in a particular environment, and the fact is they are at a higher exposure to resistant infections.”
That’s why the environmental and social causes of drug-resistant superbugs cannot be ignored, he said.
Gross and Zaman say that the next step in their research is to figure out if their findings in the lab translate to the outside world.
They hope to begin studies with research partners overseas to watch refugee camps for microplastic-related antibiotic-resistant bacteria and viruses. They also aim to figure out the exact mechanisms that allow bacteria to hold such a strong grip on plastic.
