Observations of Shear Stress Effects on Staphylococcus aureus Biofilm Formation

Authors

Erica Sherman, University of Nebraska-LincolnFollow
Kenneth W. Bayles, University of Nebraska Medical CenterFollow
Derek Moormeir, University of Nebraska Medical Center
Jennifer Endres, University of Nebraska Medical CenterFollow
Timothy Wei, University of Nebraska, LincolnFollow

ORCID IDs

https://orcid.org/0000-0002-7372-4734

Date of this Version

7-17-2019

Citation

2019 Sherman et al.

Comments

July/August 2019 Volume 4 Issue 4 e00372-19

https://doi .org/10.1128/mSphere.00372-19.

Abstract

Staphylococcus aureus bacteria form biofilms and distinctive microcolony or “tower” structures that facilitate their ability to tolerate antibiotic treatment and to spread within the human body. The formation of microcolonies, which break off, get carried downstream, and serve to initiate biofilms in other parts of the body, is of particular interest here. It is known that flow conditions play a role in the development, dispersion, and propagation of biofilms in general. The influence of flow on microcolony formation and, ultimately, what factors lead to microcolony development are, however, not well understood. The hypothesis being examined is that microcolony structures form within a specific range of levels of shear stress. In this study, laminar shear flow over a range of 0.15 to 1.5 dynes/cm2 was examined. It was found that microcolony structures form in a narrow range of shear stresses around 0.6 dynes/cm2. Further, measurements of cell density as a function of space and time showed that shear dependence can be observed hours before microcolonies form. This is significant because, among other physiologic flows, this is the same shear stress found in large veins in the human vasculature, which, along with catheters of similar diameters and flow rates, may therefore play a critical role in biofilm development and subsequent spreading of infections throughout the body.