Effect of long-lasting antimicrobial surface sprays in real-life environment

TL;DR

This study tested antimicrobial sprays in real-life settings and found they were less effective than in lab tests, possibly due to oily substances on surfaces.

Contribution

The study provides new insights into the real-world effectiveness of antimicrobial sprays and identifies a potential barrier to their efficacy.

Findings

In vitro experiments showed all sprays were effective against bacteria in suspension.

In real-life settings, no significant microbial reduction was observed after spray treatment.

Sequencing showed door openers' microbiomes were dominated by skin bacteria like Staphylococcus and Micrococcus.

Abstract

Antimicrobial surfaces have the potential to continuously self-decontaminate, which can play a key role in infection control. Various surface treatment sprays are available on the market today, differing in their chemical compositions and active ingredients. This study aimed to evaluate the effectiveness of these surface treatment sprays in real-life settings. The effects of the sprays were examined both in vitro, using bacterial suspensions, and in real-life settings. Effectiveness was measured by the number of colony-forming units (CFU) and by ATP tests. Additionally, the microbiome of one door opener was sequenced to identify the predominant microbes on that surface. Sequencing revealed that the microbiome of the door openers is mainly composed of skin bacteria. Staphylococcus (49.2%) and Micrococcus (33.6%) were the dominant genera identified in the sample. In vitro experiments demonstrated that all spray treatments were effective when tested against bacteria in suspension. However, in real-life settings, none of our measurements detected a significant reduction in microbial presence following spray treatment. We hypothesize that this discrepancy is due to the presence of a fatty substance, likely from fingerprints, on surfaces. This oily layer may act as a barrier that physically separates microbes from the treated surfaces, thereby diminishing the efficacy of the antimicrobial sprays.

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