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Updated: Jun 5, 2026
Introducing Shear Stress in the Study of Bacterial Adhesion
Published on: September 2, 2011
The effects of shear stress on isolated receptor-ligand interactions of Staphylococcus epidermidis and human plasma
Westbrook M Weaver1, Shivani Dharmaraja, Vladana Milisavljevic
1Department of Bioengineering, University of California, Los Angeles, CA, USA.
Abstract:
Staphylococcus epidermidis is an opportunistic pathogen that has been implicated in hospital-acquired infections, specifically related to implanted intravascular devices. S. epidermidis adhesion is a mechanism of colonization, leading to pathogenesis. Here we demonstrate an easily fabricated and robust parallel microfluidic platform to investigate the physiologically-relevant effects of fluid shear on S. epidermidis adhesion to human fibrinogen (hFg) with increased experimental throughput. In situ molecular patterning using fluid flow boundaries allows for isolation of the molecular interactions in highly defined shear stress environments, while keeping the device operation simple and reproducible. We characterize two modes of attachment of S. epidermidis to hFg coated surfaces. Single colonies adhere in high fractions at low shear stresses (~1 dyne cm(-2)) and adhesion decays with increasing shear. However, clusters of bacteria adhere the highest at median wall shear stress (up to 10 dyne cm(-2)), and adhesion subsequently decays above this critical shear stress. This initial characterization suggests a previously unobserved phenomenon of shear activated cell-cell adhesion in S. epidermidis, which acts to increase the overall attachment strength to hFg. Both of these modes of attachment are dependant upon the presence of intact hFg, indicating that adhesion is resultant from specific molecular recognition between the bacteria and human fibrinogen. This platform provides new insight into complex host-pathogen interactions, and will allow for further investigation of colonization and pathogenesis in more physiologically relevant conditions.
Insights
This study reveals how Staphylococcus epidermidis (S. epidermidis) adheres to human fibrinogen under varying fluid shear stress. It highlights shear-activated cell-cell adhesion, crucial for bacterial colonization in infections.
Area of Science:
- Microbiology
- Biomedical Engineering
- Host-Pathogen Interactions
Background:
- Staphylococcus epidermidis is a major cause of hospital-acquired infections, particularly with implanted devices.
- Bacterial adhesion to host surfaces is a key step in colonization and disease development.
- Understanding adhesion mechanisms under physiological conditions is critical for developing effective treatments.
Purpose of the Study:
- To develop a microfluidic platform for studying Staphylococcus epidermidis adhesion to human fibrinogen under physiologically relevant fluid shear stress.
- To investigate the effects of varying shear stress on bacterial adhesion and identify different attachment modes.
- To explore the role of shear stress in bacterial cell-cell adhesion and its impact on overall attachment strength.
Main Methods:
- Fabrication of a robust parallel microfluidic device for high-throughput experiments.
- In situ molecular patterning to create defined shear stress environments.
- Characterization of Staphylococcus epidermidis attachment to human fibrinogen at different shear stress levels.
Main Results:
- Two distinct modes of Staphylococcus epidermidis attachment to human fibrinogen were observed.
- Single bacteria adhered strongly at low shear stress (~1 dyne cm(-2)), while clusters showed maximal adhesion at median shear stress (up to 10 dyne cm(-2)).
- A phenomenon of shear-activated cell-cell adhesion was identified, enhancing bacterial attachment, and this adhesion is dependent on intact human fibrinogen.
Conclusions:
- The developed microfluidic platform enables detailed investigation of host-pathogen interactions under controlled shear conditions.
- Shear stress influences Staphylococcus epidermidis adhesion through distinct mechanisms, including shear-activated cell-cell adhesion.
- Specific molecular recognition between Staphylococcus epidermidis and human fibrinogen is essential for bacterial adhesion and colonization.
