Is a reduction in viability enough to determine biofilm susceptibility to a biocide?

Ledwoch, Katarzyna, Magoga, Maddalena, Williams, Dulcie, Fabbri, Stefania, Walsh, James ORCID: 0000-0002-6318-0892 and Maillard, Jean-Yves
(2021) Is a reduction in viability enough to determine biofilm susceptibility to a biocide? INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY, 42 (12). pp. 1486-1492.

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<h4>Objective</h4>The abundance and prevalence of dry-surface biofilms (DSBs) in hospitals constitute an emerging problem, yet studies rarely report the cleaning and disinfection efficacy against DSBs. Here, the combined impact of treatments on viability, transferability, and recovery of bacteria from DSBs has been investigated for the first time.<h4>Methods</h4>Staphylococcus aureus DSBs were produced in alternating 48-hour wet-dry cycles for 12 days on AISI 430 stainless steel discs. The efficacy of 11 commercially available disinfectants, 4 detergents, and 2 contactless interventions were tested using a modified standardized product test. Reduction in viability, direct transferability, cross transmission (via glove intermediate), and DSB recovery after treatment were measured.<h4>Results</h4>Of 11 disinfectants, 9 were effective in killing and removing bacteria from S. aureus DSBs with >4 log10 reduction. Only 2 disinfectants, sodium dichloroisocyanurate 1,000 ppm and peracetic acid 3,500 ppm, were able to lower both direct and cross transmission of bacteria (<2 compression contacts positive for bacterial growth). Of 11 disinfectants, 8 could not prevent DSB recovery for >2 days. Treatments not involving mechanical action (vaporized hydrogen peroxide and cold atmospheric plasma) were ineffective, producing <1 log10 reduction in viability, DSB regrowth within 1 day, and 100% transferability of DSB after treatment.<h4>Conclusions</h4>Reduction in bacterial viability alone does not determine product performance against biofilm and might give a false sense of security to consumers, manufacturers and regulators. The ability to prevent bacterial transfer and biofilm recovery after treatment requires a better understanding of the effectiveness of biocidal products.

Item Type: Article
Uncontrolled Keywords: Humans, Biofilms, Staphylococcus aureus, Peracetic Acid, Disinfectants, Disinfection
Divisions: Faculty of Science and Engineering > School of Electrical Engineering, Electronics and Computer Science
Depositing User: Symplectic Admin
Date Deposited: 17 Jan 2022 16:27
Last Modified: 18 Jan 2023 21:15
DOI: 10.1017/ice.2021.42
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