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. 2019 Dec;7(23):754.
doi: 10.21037/atm.2019.11.91.

Understanding the factors involved in determining the bioburdens of surgical masks

Zhiqing Liu  1 , Degang Yu  1 , Yuwei Ge  1 , Liao Wang  1 , Jingwei Zhang  1 , Huiwu Li  1 , Fengxiang Liu  1 , Zanjing Zhai  1
Affiliations

Understanding the factors involved in determining the bioburdens of surgical masks

Zhiqing Liu et al. Ann Transl Med. 2019 Dec.

Abstract

Background: Surgical site infection (SSI) continues to be one of the most common postoperative complications. In our previous study, surgical mask (SM) bioburden was identified to be a potential source of SSI. In the present study, we investigated the factors involved in SM bioburden.

Methods: Bioburdens of the disposable SM (A: medical mask; B: medical surgical mask) and newly laundered cloth SM (C) were tested by immediately making an impression of the external surface of the mask on sterile culture media. SM microstructure was observed using a scanning electron microscope (SEM). Filtering efficiency and airflow resistance were evaluated with TSI Automated Filter Tester 8130 (TSI Incorporated) according to GB/19083-2010. Whether speaking during operation and washing the face pre-operatively affect SM bioburdens was also evaluated. Surgical procedures were performed in a dynamic operation room. Fifty cases of mask use were enrolled in this study.

Results: The bioburden of mask A was the highest. The bioburden of mask B was the lowest. Mask C possessed the lowest filtering efficiency and the highest airflow resistance. SM bioburden was higher in the speaking group. SM bioburden showed no significant difference after washing the face, despite the finding that washing could significantly reduce facial bioburden.

Conclusions: Multiple factors influence SM bioburdens. Mask B showed the lowest bioburden and best protection effects. Mask C is not recommended to be used, especially considering that surgeons do not wash the cloth masks daily. Unnecessary talking during operation is not recommended, and washing the face before surgery is not strictly necessary.

Keywords: Surgical mask (SM); bioburden; mask type; speaking; washing face.

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Conflict of interest statement

Conflicts of Interest: The authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
Different mask properties. (A) The scanning electron microscope of masks A, B, and C. (B) Mask porosity. (C) Mask pore size. *, P<0.05.
Figure 2
Figure 2
Mask filter efficiency (A) and airflow resistance (B). *, P<0.05.
Figure 3
Figure 3
Representative CFUs of masks from speaking and no speaking (A), and statistical results (B). *, P<0.05. CFU, colony-forming unit.
Figure 4
Figure 4
Representative CFUs of faces and masks from face-washing and no face-washing (A), and statistical results (B,C). *, P<0.05. CFU, colony-forming unit.
Figure 5
Figure 5
Representative CFUs of different masks (A) and statistical results (B). *, P<0.05. CFU, colony-forming unit.
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