Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

The Bacterial Burden of Worn Face Masks – Observational Research and Literature Review

Version 1 : Received: 19 December 2023 / Approved: 20 December 2023 / Online: 20 December 2023 (15:14:56 CET)

How to cite: Kisielinski, K.; Wojtasik, B.; Zalewska, A.; Livermore, D. M.; Jurczak-Kurek, A. The Bacterial Burden of Worn Face Masks – Observational Research and Literature Review. Preprints 2023, 2023121576. https://doi.org/10.20944/preprints202312.1576.v1 Kisielinski, K.; Wojtasik, B.; Zalewska, A.; Livermore, D. M.; Jurczak-Kurek, A. The Bacterial Burden of Worn Face Masks – Observational Research and Literature Review. Preprints 2023, 2023121576. https://doi.org/10.20944/preprints202312.1576.v1

Abstract

We investigated and quantified bacterial accumulation in facemasks used by the general population, using 16S rRNA (Sanger Sequencing), culture and biochemical analysis along with Rose Bengal staining. Additionally, a systematic overview of the literature on face mask contamination was undertaken. We found an average bacterial load of 4.24 × 104 CFU recovered/mask, with a maximum load of 2.85 × 105 CFU. This maximum is 310 times higher than the limit value for contamination of ventilation system outlet surfaces specified by the German standard VDI 6022. Biochemical and molecular identification predominantly found Staphylococcus species (80%), including Staphylococcus aureus, along with endospore-forming Bacillus spp. Literature reports also indicate contamination of masks by bacterial and fungal opportunists of the genera Acinetobacter, Aspergillus, Alternaria, Bacillus, Cadosporium, Candida, Escherichia, Enterobacter, Enterococcus, Klebsiella (including K. pneumoniae), Micrococcus, Microsporum, Mucor, Pseudomonas, Staphylococcus and Streptococcus. Bacterial counts increase linearly with wearing duration, and prolonged use may affect the skin and respiratory microbiomes, promoting consequential eye, skin, oral and airway conditions. These aspects underscore the urgent need for further research and a risk-benefit analysis in respect of mask use, particularly given their unproven efficacy in disrupting the transmission of respiratory viruses and their adverse social consequences.

Keywords

16S rRNA gene amplicon sequencing; adverse effects; bacterial contamination; fluorescent staining; masks; N95; personal protective equipment; risk; surgical mask

Subject

Biology and Life Sciences, Immunology and Microbiology

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