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Cotton and Surgical Face Masks in Community Settings: Bacterial Contamination and Face Mask Hygiene
Lize Delanghe1, Eline Cauwenberghs1, Irina Spacova1
1Department of Bioscience Engineering, University of Antwerp, Antwerp, Belgium.
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.
Insights
Disposable and cotton face masks accumulate significant bacteria, including antibiotic-resistant strains, after use. Proper cleaning or disposal is crucial to mitigate biosafety risks associated with mask-wearing.
Area of Science:
- Microbiology
- Public Health
- Infectious Disease Epidemiology
Background:
- The widespread use of face masks during the COVID-19 pandemic necessitates an understanding of their potential for bacterial cross-contamination.
- Assessing the microbial bioburden on both disposable surgical and homemade cotton masks is essential for public safety.
- Investigating user habits regarding mask hygiene and cleaning practices is important for risk assessment.
Purpose of the Study:
- To analyze the bacterial bioburden on disposable surgical and cotton face masks after a period of wear.
- To identify the types of bacteria present on used face masks and assess their antibiotic resistance profiles.
- To evaluate the impact of mask wearing on the microbiome of the anterior nares and facial skin.
Main Methods:
- Culture-based methods and 16S rRNA gene amplicon sequencing were employed to analyze microbial communities on masks worn by 13 healthy volunteers for 4 hours.
- Bacterial isolates were tested for resistance to common antibiotics like ampicillin and erythromycin.
- A large-scale survey (nearly 25,000 participants) assessed face mask usage, cleaning habits, and preferences in the Flemish population.
Main Results:
- Cotton masks harbored a higher average bacterial load (1.46 × 10^5 CFU/mask) compared to surgical masks (1.32 × 10^4 CFU/mask).
- Dominant bacterial genera included Bacillus, Staphylococcus, Acinetobacter, Roseomonas, Paracoccus, Enhydrobacter, and Streptococcus, with 43% of isolates showing antibiotic resistance.
- Mask wearing showed a trend toward altering the microbiome diversity of the anterior nares and cheeks; only 21% of surveyed individuals cleaned cotton masks daily.
Conclusions:
- Used face masks, particularly cotton ones, accumulate significant bacterial loads, including potentially pathogenic and antibiotic-resistant bacteria.
- Effective sterilization methods include boiling at 100°C, washing at 60°C with detergent, or steam ironing.
- Clear public guidelines on proper mask disposal and sterilization are crucial to mitigate biosafety risks, alongside continued physical distancing and ventilation.
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