Disinfection: antibacterial coating on surfaces in the ICU

All hospitalized patients are susceptible to contracting a nosocomial infection, with ICU patients being particularly at risk. The effects of these hospital-acquired infections are often more dangerous than the original reason for the in-patient hospitalization. The "PACMAN" project is now testing an antimicrobial coating for frequently used contact surfaces at high risk of pathogen transmission.

In this MEDICA-tradefair.com interview, Prof. Wolfgang Bäumler explains how the coating works, describes the testing process, and reveals his hopes for the "PACMAN" project.

Prof. Bäumler, what is the goal of the recently launched "PACMAN" project?

Prof. Wolfgang Bäumler: Our objective is to reduce the microbiological load on intensive care unit surfaces via an antimicrobial coating. Besides quantifying microbial pathogens on surfaces, we also plan to use whole genome sequencing to track the spread of bacteria across hospital wards.

It has been known for many years that apart from human-to-human transmission via hand contact for example, surfaces in the immediate vicinity of a patient also play an important role in the transfer of pathogens. Human pathogens can persist on surfaces for days or even weeks and leave a reservoir from which infection can be transmitted to another person and subsequently spread.

How does the coating work?

Bäumler: The basic idea is for the coating to prevent or at least reduce the formation of reservoirs and consequently control the spread of pathogens. The surfaces are coated with a solution containing a photodynamic dye molecule. It dries quickly and leaves a durable, thin coating behind. When the coated surface is exposed to light, it generates a highly reactive oxygen (singlet oxygen) that kills bacteria and viruses on the surface.

We have already tested the technology in two hospitals as part of a previous project. The comparison of coated and uncoated surfaces has shown that the bacterial load is drastically lower on coated surfaces. Of course, hospitals already apply surface disinfection standards, but this entails cleaning staff that regularly sanitizes the surfaces. Since the effect of surface disinfection at hospitals disappears immediately after application, the surface remains unprotected until the next application. The benefit of an antimicrobial coating is that it provides permanent protection without the involvement of staff. That also means, surface disinfection and antimicrobial coating complement each other.

How long does the effect last?

Bäumler: It lasts at least one year. The coating is designed to either be painted on or retroactively applied by wiping it on the surface.

What types of pathogens does the coating protect against?

Bäumler: It basically protects against all infections that typically occur in hospitals, of which there are many. We focus on resistant strains such as MRSA and VRE, but also pay attention to non-resistant bacteria that cause issues. Gram-negative bacteria are likewise an increasing threat.

Our project originated before the coronavirus outbreak, but we are also testing the effect on enveloped viruses in-house, which includes SARS-CoV-2. There are clear indications of effectiveness, but this is not an explicit part of our current project.

The project is still in its early stages. What is the schedule and who is involved?

Bäumler: This is a three-year project with the clinical field study scheduled to last one year. We conduct the study in two intensive care units: in one unit, we coat the contact surfaces, while the other unit serves as a control with uncoated surfaces. Then we constantly compare whether the transmission on the coated surfaces is effectively lower than on the uncoated surfaces.

We at the University Hospital are currently identifying the contact areas that are potential hotspots for transmission of infections and collaborate with two companies from Regensburg.

Dyphox has developed the coating and will equip our intensive care unit this fall. We also team up with PreSens GmbH, which is simultaneously developing a method for the rapid detection of pathogens on surfaces. It uses a fluorescent sensor foil combined with a camera system to visualize the oxygen consumption by pathogens.

The combined technologies are designed to measure the bacterial load on the surfaces once a week for several months. The research hypothesis is that the antimicrobial coating reduces both the number of bacteria and the spread of these pathogenic microorganisms in hospital wards. Of course, we also hope that this will reduce the incidence of nosocomial infections.