Cotton and Surgical Face Masks in Community Settings: Bacterial Contamination and Face Mask Hygiene.

Lize Delanghe,Ilke De Boeck,Wannes Van Beeck,Eline Cauwenberghs,Koen Pepermans,Veronique Verhoeven,Ingmar Claes,Sarah Lebeer,Irina Spacova,Dieter Vandenheuvel

doi:10.3389/fmed.2021.732047

Abstract

During the current COVID-19 pandemic, the use of face masks has become increasingly recommended and even mandatory in community settings. To evaluate the risk of bacterial cross-contamination, this study analyzed the bacterial bioburden of disposable surgical masks and homemade cotton masks, and surveyed the habits and face mask preferences of the Flemish population. Using culture approaches and 16S rRNA gene amplicon sequencing, we analyzed the microbial community on surgical and/or cotton face masks of 13 healthy volunteers after 4 h of wearing. Cotton and surgical masks contained on average 1.46 × 105 CFU/mask and 1.32 × 104 CFU/mask, respectively. Bacillus, Staphylococcus, and Acinetobacter spp. were mostly cultured from the masks and 43% of these isolates were resistant to ampicillin or erythromycin. Microbial profiling demonstrated a consistent difference between mask types. Cotton masks mainly contained Roseomonas, Paracoccus, and Enhydrobacter taxa and surgical masks Streptococcus and Staphylococcus. After 4 h of mask wearing, the microbiome of the anterior nares and the cheek showed a trend toward an altered beta-diversity. According to dedicated questions in the large-scale Corona survey of the University of Antwerp with almost 25,000 participants, only 21% of responders reported to clean their cotton face mask daily. Laboratory results indicated that the best mask cleaning methods were boiling at 100°C, washing at 60°C with detergent or ironing with a steam iron. Taken together, this study suggests that a considerable number of bacteria, including pathobionts and antibiotic resistant bacteria, accumulate on surgical and even more on cotton face masks after use. Based on our results, face masks should be properly disposed of or sterilized after intensive use. Clear guidelines for the general population are crucial to reduce the bacteria-related biosafety risk of face masks, and measures such as physical distancing and increased ventilation should not be neglected when promoting face mask use.

Highlights

During the current coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the use of protective face masks has become increasingly recommended or even mandatory in community settings outside hospitals and care facilities [1, 2]
After 4 h of wearing, the cotton masks contained a mean of 1.38 × 105 colony forming unit (CFU)/mask (SD = 1.95 × 105) counted on Lysogeny Broth (LB) and 1.53 × 105 CFU/mask (SD = 1.96 × 105) on Brain Heart Infusion (BHI) growth medium
The surgical masks contained a mean of 1.79 × 104 CFU/mask (SD = 1.63 × 104) on LB and 2.18 ×

Summary

Introduction

During the current coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the use of protective face masks has become increasingly recommended or even mandatory in community settings outside hospitals and care facilities [1, 2]. One meta-analysis and systematic review has concluded that the use of masks by healthcare workers and non-healthcare workers reduces the risk of respiratory virus transmission (including SARS, influenza virus, H1N1, and SARS-CoV-2) with 80 and 47%, respectively [2]. This significant protective effect of face masks in community and health care settings was not found by other studies [1, 7, 12,13,14,15,16,17]. Masks seem less effective in protecting the wearer from being infected [20], but they could reduce the risk of virus transmission when worn consistently [10, 21, 22]

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Discussion

Conclusion