Effect of disinfectant formulation and organic soil on the efficacy of oxidizing disinfectants against biofilms

D. Chowdhury, A. Rahman, H. Hu, S. O. Jensen, A. K. Deva, K. Vickery*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    17 Citations (Scopus)
    179 Downloads (Pure)


    Background: Biofilms that develop on dry surfaces in the healthcare environment have increased tolerance to disinfectants. This study compared the activity of formulated oxidizing disinfectants with products containing active ingredients against Staphylococcus aureus dry-surface biofilm (DSB) alone. Methods: DSB was grown in the CDC bioreactor with alternating cycles of hydration and dehydration. Disinfectant efficacy was tested before and after treatment with neutral detergent for 30 s, and in the presence or absence of standardized soil. Biofilms were treated for 5 min with peracetic acid (Surfex and Proxitane), hydrogen peroxide (Oxivir and 6% H2O2 solution) and chlorine (Chlorclean and sodium dichloroisocyanurate tablets). Residual biofilm viability and mass were determined by plate culture and protein assay, respectively. Findings: Biofilm viability was reduced by 2.8 log10 for the chlorine-based products and by 2 log10 for Proxitane, but these products failed to kill any biofilm in the presence of soil. In contrast, Surfex completely inactivated biofilm (6.3 log10 reduction in titre) in the presence of soil. H2O2 products had little effect against DSB. Biofilm mass removed in the presence and absence of soil was <30% by chlorine and approximately 65% by Surfex. Detergent treatment prior to disinfection had no effect. Conclusion: The additives in fully formulated disinfectants can act synergistically with active ingredients, and thus increase biofilm killing whilst decreasing the adverse effect of soil. It is suggested that purchasing officers should seek efficacy testing results, and consider whether efficacy testing has been conducted in the presence of biological soil and/or biofilm.

    Original languageEnglish
    Pages (from-to)e33-e41
    Number of pages9
    JournalJournal of Hospital Infection
    Issue number1
    Publication statusPublished - 1 Sep 2019

    Bibliographical note

    Copyright the Author(s) 2018. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


    • Biofilms
    • Disinfectant efficacy
    • Disinfection
    • Dry hospital surfaces
    • Oxidizing disinfectants
    • Removing biofilms


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