Staphylococcus aureusbiofilm formation and tolerance to antibiotics in response to oscillatory shear stresses of physiological levels

Abstract

Bacterial infections in the blood system are usually associated with blood flow oscillation generated by some cardiovascular pathologies and insertion of indwelling devices. The influence of hydrodynamically induced shear stress fluctuations on the Staphylococcus aureus biofilm morphology and tolerance to antibiotics was investigated. Fluctuating shear stresses of physiologically relevant levels were generated in wells of a six-well microdish agitated by an orbital shaker. Numerical simulations were performed to determine the spatial distribution and local fluctuation levels of the shear stress field on the well bottom. It is found that the local biofilm deposition and morphology correlate strongly with shear stress fluctuations and maximum magnitude levels. Tolerance to killing by antibiotics correlates with morphotype and is generally higher in high shear regions.

Induction of Attachment-Independent Biofilm Formation and Repression ofhfqExpression by Low-Fluid-Shear Culture of Staphylococcus aureus

“…Furthermore, in response to varied levels of fluid flux, variations on the staphylococcal cell have been investigated using flow chambers to determine changes in the presence of microbial surface components recognizing adhesive matrix molecules, MSCRAMMs, which are involved in the ability of S. aureus to colonize (53). These investigations demonstrated that the S. aureus MSCRAMMs function in a shear-dependent manner, whereby the binding efficiency to host factors peaks under conditions of low fluid shear (50,54).Previous investigations have also demonstrated the ability of S. aureus to sense and respond to fluid shear flux by altering biofilm architecture (31,63). Specifically, studies of indwelling medical devices have indicated that S. aureus is an efficient biofilm former under various degrees of fluid shear (31, 63).…”

“…Previous investigations have also demonstrated the ability of S. aureus to sense and respond to fluid shear flux by altering biofilm architecture (31,63). Specifically, studies of indwelling medical devices have indicated that S. aureus is an efficient biofilm former under various degrees of fluid shear (31,63).…”

“…Specifically, studies of indwelling medical devices have indicated that S. aureus is an efficient biofilm former under various degrees of fluid shear (31,63). The impact of fluid shear on staphylococcal biofilms has resulted in correlations between physiological levels of oscillatory shear stress and biofilm morphology and tolerance to antibiotics (31).…”

“…The impact of fluid shear on staphylococcal biofilms has resulted in correlations between physiological levels of oscillatory shear stress and biofilm morphology and tolerance to antibiotics (31). Those investigations determined that the most turbulent flow conditions resulted in the thickest biofilm morphology and highest level of antibiotic resistance (31). Moreover, in response to fluid shear, the viscoelasticity of S. aureus biofilms permits them to remain attached yet undergo rolling migration, thereby promoting bacterial dispersal while remaining in the protected biofilm state (63).…”

Numerical Simulation of Fluid Flow and Hydrodynamic Analysis in Commonly Used Biomedical Devices in Biofilm Studies

“…The oscillating flow behavior arising in 6-well plates can represent the physiological flows observed in vivo. Both increased shear stress levels and flow oscillation associated with plate motion were observed to contribute to biofilms formation (Kostenko et al, 2010). …”