Nosocomial infections, i.e. infections acquired by patients in connection with a medical procedure, but also infections of employees in medical facilities (including hospitals, doctors’ surgeries, care facilities), pose an extraordinary challenge not only in the event of major outbreaks, but also against the background of the increasing number and spread of antibiotic-resistant pathogens.

Surfaces, including floors, can act as a source of contamination. Bacteria and viruses can be transferred from these surfaces to patients or infection-relevant surfaces and instruments, for example via hands and care aids or through dust and air turbulence.

Proper surface cleaning and disinfection therefore makes a significant contribution to reducing the risk of infection. As floor surfaces make up the largest part of all surfaces and their contamination is many times higher than that of other surfaces, floor cleaning and disinfection are of particular importance.

Combination products (disinfectant cleaners containing cleaning and disinfecting agents) are predominantly used for the disinfecting cleaning of floor coverings. If the treated surfaces are completely wetted and the recommended application concentration and contact time are followed, these products will provide adequate disinfection.

Complete wetting is also necessary for more effective soil removal to dissolve or suspend soil. A method for monitoring surface wetting during the wiping process can therefore significantly increase process reliability.

The aim of the research project were hydrochromic surfactant systems that enable visual monitoring of surface wetting during cleaning/disinfection processes. Based on an intensive literature search, dyes were selected that change their absorption behaviour when dissolved in water and thus change from a transparent to a coloured state (hydrochromic dyes).

Such dyes were incorporated into the polar head group of a suitable surfactant system (fatty alcohol ethoxylate) to obtain hydrochromic surfactant systems. The hydrochromic surfactant systems were successfully incorporated into disinfectant cleaner formulations.

During maintenance cleaning, the hydrochromic surfactant systems accumulate on the treated surfaces together with the other disinfectant cleaner surfactants and the disinfectant active ingredients, where they remain until the next cleaning/disinfection process.

Due to the colour of the hydrochromic surfactant systems in the dissolved state, it is therefore possible to directly differentiate between cleaned/disinfected areas and areas that still need to be cleaned/disinfected.

As the hydrochromic surfactant systems change to a transparent state immediately after the drying process, it is also possible to visually monitor compliance with the contact time. Due to the transparency of the hydrochromic surfactant systems in the dry state, any impairment of the visual appearance of treated surfaces between two cleaning/disinfection processes can be safely ruled out.

The research report is available on request from the wfk – Cleaning Technology Institute