Staphylococcus aureus, an opportunistic human pathogen, is commonly associated with nosocomial infections and often colonizes medical devices such as catheters. Using glass flow cells, biofilms can be monitored in situ microscopically.
This is a 11.5-hour time lapse video sequence showing a side view of a Staphylococcus aureus biofilm microcolony rolling along the side wall of a square glass tube. Water containing brain-heart infusion broth was flowing through the tube at a flow rate of 1 ml/min, giving an average flow velocity of 1.7 cm/s. The biofilm microcolony appeared to be attached to the glass by sticky appendages or "tethers". The rolling motion appeared to be caused by the continual attachment and detachment of the biofilm from the glass surface. First the microcolony detaches from the upstream side, where presumably the shear force overcomes the attachment force of the tether. It then jerks forward in a rolling motion and tethers reattach at the downstream side.
The migration of bacterial microcolonies along the lumen of catheters (tubes used to deliver fluids into the body or drain fluids from the body), endotracheal tubes (tubes used to maintain an airway), or dental unit water lines may be an important consideration in the dissemination of pathogens such as S. aureus into patients. In industrial systems, the movement of biofilms along the walls of process pipes may result in the spread of contamination to other parts of the system. By moving along the pipe wall, the biofilm can spread without detaching and entering a planktonic (free swimming or floating) phase in which the bacteria are often more susceptible to antimicrobial agents such as antibiotics or biocides.
Acknowledgments: This work was supported by the National Institutes of Health grant RO1 GM60052 and the W. M. Keck Foundation. The movie sequence is also available at the ASM MicrobeLibrary (www.microbelibrary.org).
Movie authors: Rupp CJ, Wilson S, and Stoodley P (2003_m03)
Reference: Rupp CJ, Fux C, and Stoodley P, "Viscoelasticity of Staphylococcus aureus biofilms in response to fluid shear resists detachment and facilitates rolling migration," Appl Environ Microbiol, 2005; 71(4):2175-2178
Klapper I, Rupp CJ, Cargo R, Purevdorj B, and Stoodley P, "A viscoelastic fluid description of bacterial biofilm material properties," Biotechnol Bioeng, 2002; 80:289-296.
Stoodley P, Lewandowski Z, Boyle JD, and Lappin-Scott HM, "Structural deformation of bacterial biofilms caused by short term fluctuations in flow velocity: An in situ demonstration of biofilm viscoelasticity," Biotechnol Bioeng, 1999; 65:83-92.