Researchers have found that a well-known hospital bacterium can actually consume the plastics used in sutures, stents, and surgical mesh. This ability allows the microbe to potentially adhere more stubbornly to medical devices and persist longer on surfaces in healthcare settings.
A team from Brunel University London, studying a patient-derived strain of Pseudomonas aeruginosa, discovered that this pathogen breaks down polycaprolactone (PCL)—a biodegradable plastic widely used in modern medical applications.
This finding questions the belief that clinical polymers are immune to microbial breakdown.
Turning hospital plastics into food
The team identified a single enzyme, dubbed Pap1, responsible for this plastic-degrading function. In controlled lab conditions, Pap1 was able to diminish a thin layer of PCL by 78% within a week. The bacterium then utilized the resulting fragments as a carbon source.
“This means we need to rethink how pathogens behave in hospitals,” noted Professor Ronan McCarthy, who spearheaded the research.
“Plastics, including surfaces, could serve as nutrition for these bacteria. Pathogens with this capacity might survive longer in hospital settings, which raises concerns about any medical device that contains plastic.”
PCL is prized for its flexibility, melting point, and ability to dissolve in the body over time, making it ideal for various medical uses such as resorbable sutures and tissue scaffolds.
Previously, it was understood that PCL would degrade only via hydrolysis and natural metabolic processes, but Pap1 demonstrates that microbes can expedite this degradation while also taking advantage of it.
Plastic boosts bacterial defenses
In digesting plastics, P. aeruginosa gains more than just sustenance. The broken pieces of polymer contribute to forming tougher biofilms—those resilient layers that can withstand disinfectants, immune responses, and many antibiotics.
Infections related to catheters and ventilators are already some of the most difficult to treat in healthcare environments. The breakdown of PCL could enhance the bacteria’s defenses, complicating treatment even further.
The World Health Organization has flagged P. aeruginosa as a top “critical” pathogen requiring new drug development, given its rapid adaptability and ability to thrive in less-than-ideal conditions.
This study suggests that plastic could be an unexpected source of energy, tipping survival in favor of this microorganism.
More bacteria may digest plastic
The researchers analyzed genetic databases and identified similar enzyme sequences in other bacteria commonly found in intensive care units.
While only PCL digestion was confirmed, these sequences hint that other plastics like polyurethane and polyethylene terephthalate—used in various medical applications—might also be at risk.
“The bacterium’s ability to degrade plastics likely aids its survival on surfaces, possibly contributing to hospital outbreaks. We should focus on developing plastics that are less digestible by microbes, and consider screening pathogens for these enzymes, particularly during mysterious, ongoing outbreaks,” McCarthy suggested.
This issue affects more than just operating rooms; materials like cardiac stents, breast implants, and dental membranes all rely on polymers for strength and flexibility. If these materials can be metabolized, hidden infections could smolder, going unnoticed until biofilms become significant.
Designing safer plastics
One potential approach is to redesign polymers to make their chemical structures more resistant to enzymatic breakdown. Another could involve coating device surfaces with materials that inhibit bacterial growth.
Any solutions need to maintain the mechanical properties that make PCL appealing while ensuring they don’t degrade inside the body.
Research chemists might also explore Pap1 for insights, as understanding its active site could reveal what molecular structures attract or repel it, guiding future development of safer hospital plastics.
Rethinking hospital surveillance
Hospitals already collect samples from various surfaces. However, the new findings suggest that laboratories should start looking specifically for plastic-degrading enzymes.
Environmental samples that test positive could illuminate outbreaks that have defied standard tracking methods. Cleaning procedures may also need to adapt; just removing visible dirt might not suffice if bacteria can hide within the polymer and consume it.
McCarthy underscores that this research is just the initial phase. They focused on one strain, one enzyme, and one polymer in a controlled environment. Real-world settings feature mixed microbes, fluctuating temperatures, and diverse materials.
“Plastic is ubiquitous in modern medicine. It turns out, some pathogens have evolved to break it down, which calls for a closer look at its impact on patient safety,” he concluded.
Next experiments on the horizon
Future investigations will assess used devices for signs of microbial degradation, track enzyme genes across hospital settings, and expose other medical plastics to potential degraders.
Animal studies might reveal whether in-body degradation affects implant strength or inflames surrounding tissue. Concurrent research on coatings and polymer chemistry will work on developing better defenses.
The current picture, though, is somewhat disconcerting: a superbug residing on a catheter and slowly consuming the very tube meant to aid in recovery, fortifying itself in the process. This revelation challenges existing beliefs and suggests that, in the quiet corners of a hospital, plastic might not be as inert as once thought; instead, it could serve as a hidden buffet for lurking pathogens.
The study appears in the journal Cell Reports.
