# A novel method of simulated-use surface disinfection efficacy testing as Phase 3 Step 1 approach

## TL;DR

This study introduces a new simulated-use test for surface disinfectants that better reflects real-world hospital conditions, improving the accuracy of efficacy assessments.

## Contribution

A standardized Phase 3 Step 1 simulated-use test method incorporating clinical strains, realistic contamination, and user application is developed and validated.

## Key findings

- The touch-transfer contamination method was reproducible across different surfaces.
- Microbial recovery varied between test runs and participants, indicating variability in application.
- The new method better represents clinical disinfection practices compared to current standardized tests.

## Abstract

Standard laboratory tests for surface disinfectants often fail to reflect real-life clinical conditions, potentially overestimating efficacy. Simulated-use testing that incorporates clinical strains, realistic contamination and user application may provide a more accurate reflection of in-use performance in healthcare settings.

The aim of this study was to develop and validate a standardized, reproducible Phase 3 Step 1 simulated-use surface disinfection test that incorporates clinically relevant organisms, hospital-representative surfaces, and realistic application methods.

Based on EN 16615:2015, the test method was modified to reflect hospital conditions more closely. Clinically isolated outbreak strains of Staphylococcus aureus, Enterococcus faecium and Acinetobacter baumannii were used. Contamination was applied via a touch-transfer method. Surface materials included hospital-relevant substrates, and disinfectant wipes were applied by trained volunteers to simulate routine cleaning practices.

The touch-transfer contamination method was reproducible, and no significant differences were observed in drying or water controls across different surfaces. Wiping speed and contact pressure did not correlate with efficacy. However, microbial recovery varied across test runs and participants. The test method presented here allows for efficacy testing of commercial disinfectants.

A Phase 3 Step 1 simulated-use test was established, which incorporates micro-organisms isolated from the application area, surfaces representative of the application area, and where the product is applied by trained participants. This internally validated method better represents clinical disinfection practices compared with current standardized tests and may support improved assessment of surface disinfectant efficacy under conditions approximating real-world hospital use.