London, England — A recent discovery by researchers at Brunel University has revealed a surprising ability of the notorious hospital bacterium Pseudomonas aeruginosa: it can digest plastics often used in medical devices such as sutures and stents. This revelation raises important questions about the safety and longevity of these devices in clinical settings, as the bacteria may utilize the polymers as a source of nourishment, enabling them to thrive on surfaces and potentially complicate infections.
The study focused on a strain of Pseudomonas aeruginosa derived from a patient, uncovering its capability to dismantle polycaprolactone (PCL), a biodegradable plastic well-regarded in modern medical applications. Researchers identified a specific enzyme, dubbed Pap1, that efficiently breaks down PCL. In controlled laboratory tests, Pap1 reduced a thin film of the plastic by 78% within just a week, demonstrating how the bacterium transforms the polymer into a food source.
This finding challenges previous assumptions that hospital-grade plastics were resistant to microbial degradation. “We need to rethink how pathogens interact with their environment in medical settings,” said Professor Ronan McCarthy, who led the research. “The ability of these bacteria to metabolize plastics could enhance their survival and resilience, complicating treatment options for patients.”
PCL is favored in medical procedures due to its unique properties—it is flexible, melts at low temperatures, and gradually breaks down in the human body. Previously, medical professionals believed that it would only dissolve through natural processes, such as hydrolysis. This new research indicates that microbes can expedite that breakdown while also extracting nutrients from the material.
Beyond nourishment, the breakdown of PCL appears to strengthen the bacteria’s defenses. By consuming the plastic, Pseudomonas aeruginosa can create tougher biofilms—sticky layers of bacteria that are notably resistant to disinfectants and antibiotics. These biofilms can complicate common hospital-associated infections, making conditions like ventilator-associated pneumonia and catheter-related urinary tract infections even more challenging to manage.
The World Health Organization identifies Pseudomonas aeruginosa as a top-tier pathogen of critical concern, due to its rapid evolution and persistence in sterile environments. This study suggests that the breakdown of hospital plastics could serve as an unexpected energy source for the bacteria, further tipping the balance in their favor.
The researchers also investigated other bacterial strains and found genetic clues that indicate similar plastic-digesting enzymes may be present in bacteria that also linger in intensive care units. Although the study primarily demonstrated PCL degradation, it raises concerns that other commonly used plastics, such as polyurethane and polyethylene terephthalate, might also be susceptible to microbial attack.
McCarthy emphasized the need for hospitals to reconsider their materials. “This opens the door to exploring plastics that are more resilient against microbial degradation, as well as developing screening methods for bacteria harboring these enzymes during unexplained outbreaks,” he said. The implications of this research extend far beyond surgical settings, affecting devices such as cardiac stents and dental implants.
In response to these findings, researchers are contemplating redesigning polymers to enhance their resistance to enzymatic degradation. Another potential solution is to apply coatings that deter bacterial colonization while maintaining the desirable mechanical properties of the materials.
Current infection control protocols focus on sanitizing surfaces and equipment, but with this new understanding, hospitals may need to adopt more targeted strategies. Routine microbial surveillance could benefit from including enzyme testing, potentially leading to greater insight into outbreaks that have baffled traditional methods of detection.
While the study examined just one strain and one enzyme in a controlled setting, its implications are far-reaching. Future research will explore a wider array of medical plastics and their interactions with bacteria, possibly unearthing new approaches to enhance patient safety amidst evolving microbial threats. The research was published in Cell Reports and signals a crucial turning point in understanding the dynamic relationship between medical devices and hospital pathogens.