Quantitative Assessment of Microbial Transmission onto Environmental Surfaces Using Thermoresponsive Gelatin Hydrogels as a Finger Mimetic under In Situ‐Mimicking Conditions

A novel method for the quantitative assessment of pathogenic bacteria transmission is established using thermoresponsive gelatin as a finger-mimetic. The HydroTouch test reveals that methicillin-resistant S. aureus is highly transferable onto stainless steel compared to E. coli and P. aeruginosa. Quaternary ammonium-based antimicrobial coatings on stainless steel efficiently reduce microbial transmission efficiency under conditions closely mimicking real-life scenarios.

Abstract

Surface-mediated transmission of pathogens plays a key role in healthcare-associated infections. However, proper techniques for its quantitative analysis are lacking, making it challenging to develop novel antimicrobial and anti-fouling surfaces to reduce pathogen spread via environmental surfaces. This study demonstrates a gelatin hydrogel-based touch transfer test, the HydroTouch test, to evaluate pathogen transmission on high-touch surfaces under semi-dry conditions. The HydroTouch test employs gelatin as a finger mimetic, facilitating testing with pathogenic bacteria under controlled conditions. The thermoresponsive sol–gel transition of gelatin allows easy recovery and quantification of bacteria before and after testing. The HydroTouch test demonstrates that methicillin-resistant Staphylococcus aureus has a high transmission efficiency of ≈16% onto stainless steel, compared to <3% for Escherichia coli or Pseudomonas aeruginosa. Polyurethane surfaces exhibit strong resistance to bacterial contamination with a transmission efficiency of ≈0.6%, while polytetrafluoroethylene shows a transmission efficiency approximately four times higher than polyurethane. Additionally, quaternary ammonium-based antimicrobial coatings reduce the transmission efficiency of live bacteria on stainless steel to ≈4% of the original level. The HydroTouch test provides a reliable method for assessing pathogen transmission on various surfaces under semi-dry settings, supporting the development of effective antimicrobial, anti-transmission coatings to reduce healthcare-associated infections.