Bacterial Adhesion and Biofilm Formation: Hydrodynamics Effects

Abstract

The effectiveness of biomedical surfaces may be highly affected by the hydrodynamic condition. Surfaces releasing antimicrobial substances when exposed to flow may exhibit shorter lifetimes than at static conditions. Likewise, depending on the fluid flow surrounding the surface, contact-killing surfaces that are adhesive for bacterial cells may be covered by bacterial debris, which decreases their antimicrobial activity. To evaluate the anti-adhesive and antimicrobial performance of novel biomedical materials, a number of flow devices have been designed to recreate in vivo flow conditions. Shear stress and flow rate can be accurately controlled and varied in these in vitro flow systems, which requires prior knowledge of the flow dynamics inside the platform. After limiting their operational range, modified Robbins devices, flow chambers and microfluidic devices are suggested as experimental setups to mimic the flow behavior in urinary catheters and stents.

Towards a better understanding of the effect of protein conditioning layers on microbial adhesion: a focused investigation of fibronectin and bovine serum albumin layers on SiO2 surfaces

“…Variation of the wall shear stress is particularly interesting and enlightening, as the very low wall shear stresses simulate conditions representative of slow-flowing implants, such as ocular ones, while the high wall shear stresses are typical of high-flowing implants, similar to urinary catheters. 34–36…”

“…This is a very large step ahead to simulation of wall shear stresses comparable to those exerted on implants in the human body. 34–36 A schematic representation of the experimental set-up is shown in Fig. 1.…”

“…The results are presented as fraction of the adhered cells counted on proteins-conditioned coverslips (N protein-conditioned ) relative to those adhered on non-conditioned ones (control, N SiO 2 ), according to formula (1): This is a very large step ahead to simulation of wall shear stresses comparable to those exerted on implants in the human body. [34][35][36] A schematic representation of the experimental setup is shown in Fig. 1.…”

Lipoxin A4 promotes antibiotic and monocyte bacterial killing in established Pseudomonas aeruginosa biofilm formed under hydrodynamic conditions

“…This is important as biofilms are not formed under static conditions in the human body (e.g., urinary tract). In addition, shear stress can increase the adhesion time of bacteria when forming biofilms 13 and flow can influence the transport rates of oxygen to the biofilm 14 . Therefore, we believe that is imperative to extend studies into biofilms grown under hydrodynamic conditions 15 …”

“…In addition, shear stress can increase the adhesion time of bacteria when forming biofilms 13 and flow can influence the transport rates of oxygen to the biofilm. 14 Therefore, we believe that is imperative to extend studies into biofilms grown under hydrodynamic conditions. 15 In addition to being a barrier against leukocytes, P. aeruginosa biofilms impair neutrophil mobility out of the biofilm, increase neutrophil degranulation, and increase respiratory burst.…”