Impact of mask wearing on cultivable conjunctival bacteria in Chinese healthcare workers

Abstract This study investigated the temporal impact of mask wearing on cultivable conjunctival bacteria among healthcare workers. Conjunctival samples were collected from 48 participants, who were randomly assigned to wear surgical masks or KN95 respirators. Sampling occurred at baseline (T0, no mask), after 8 h (T1), and after one week of daily wear (T2, ≥ 8 h/day). Microbial cultures were analyzed using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry. The viable bacteria were of low diversity, dominated by Firmicutes, Actinobacteria, and Proteobacteria, encompassing seven families. Staphylococcaceae, Bacillaceae, and Corynebacteriaceae were most prevalent. In the KN95 group, Staphylococcaceae relative abundance was significantly higher at T2 than at T1 ( P = 0.009). In the surgical mask group, Corynebacteriaceae abundance was significantly higher at T2 versus T0 and T1, while Bacillaceae was lower (all P < 0.01). Significant differences in Bacillaceae across all timepoints were unique to the KN95 group (all P < 0.01). At T1, Staphylococcaceae abundance was higher in the surgical mask group, while Bacillaceae was lower compared to the KN95 group ( P = 0.025 and P = 0.023, respectively). At T2, Corynebacteriaceae abundance was significantly higher in the surgical mask group ( P = 0.010). These findings raise the possibility that mask wearing may induce subtle, mask-type-dependent alterations in the cultivable conjunctival bacteria. Further study with a control group is warranted.