title: Hydrodynamic shear stress to remove Listeria monocytogenes biofilms from stainless steel and polytetrafluoroethylene surfaces.
abstract: OBJECTIVE
  To calculate the shear stress needed to remove sessile Listeria monocytogenes cells from stainless steel (SS) and polytetrafluoroethylene (PTFE) surfaces.
  
  
  RESULTS
  Listeria monocytogenes biofilms were formed on SS and PTFE surfaces. Shear stress was calculated using a radial flow chamber device and cells quantified by staining with 4',6-diamidino-2-phenylindole. Results showed that shear stress between 24 and 144 N m(-2) removed up to 98% of cells from SS surfaces. PTFE presents a very hydrophobic surface, and a significant lower removal (P < 0.05) of only 63% was achieved; moreover, on PTFE discs, detachment of L. monocytogenes biofilms was more efficient at a lower shear stress (between 8.6 and 34 N m(-2) ).
  
  
  CONCLUSIONS
  Water flow is more effective in removing L. monocytogenes biofilms from SS surfaces than from PTFE materials.
  
  
  CONCLUSIONS
  This work clearly demonstrates that water flow does not have the same efficiency in removing cells from different material surfaces and shows the need to optimize cleaning and sampling procedures by considering the conditions in which cells attach to surfaces and the physicochemistry of the surfaces.
authors.affiliation: Centre for Biological Sciences, University of Southampton, Life Sciences Building, Highfield Campus, Southampton, SO17 1BJ, UK. M.S.Giao@soton.ac.uk
authors.forename: M S
authors.initials: MS
authors.lastname: Gião
authors.forename: C W
authors.initials: CW
authors.lastname: Keevil
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms; D004203:Disinfection / Q000379:methods; D005516:Food Microbiology; D057446:Hydrodynamics; D057927:Hydrophobic and Hydrophilic Interactions; D008089:Listeria monocytogenes / Q000254:growth & development*; D011138:Polytetrafluoroethylene; D033081:Shear Strength; D013193:Stainless Steel; D013314:Stress, Mechanical; D014867:Water
chemical_list: D014867:Water; D013193:Stainless Steel; D011138:Polytetrafluoroethylene