Most bacteria in nature take the form of biofilms. Bacteria are single-celled organisms, but they rarely live alone, said John Younger, associate chair for research in the Department of Emergency Medicine at the U-M Health System.
The new tool is a microfluidic device, also known as a "lab-on-a-chip." Representing a new application of microfluidics, the device measures biofilms' resistance to pressure. Biofilms experience various kinds of pressure in nature and in the body as they squeeze through capillaries and adhere to the surfaces of medical devices, for example.
The U-M microfluidic device, made from a flexible polymer, allows researchers to study minute samples of between 50 and 500 bacterial cells that form biofilms of 10-50 microns in size. A micron is one-millionth of a meter. A human hair is about 100 microns wide.
Such small samples behave in the device as they do in the body. Tools that require larger samples don't always give an accurate picture of how a particular substance behaves on the smallest scales.
The researchers found that the biofilms they studied had a greater elasticity than previous methods had measured. They also discovered a "strain hardening response," which means that the more pressure they applied to the biofilms, the more resistance the materials put forth.
If doctors and engineers can gain a greater understanding of how biofilms behave, they could perhaps design medical equipment that is more difficult for the bacteria to adhere to, Younger said.
The experiments were performed on colonies of Staphylococcus epidermidis and Klebsiella pneumoniae, which are known to cause infections in hospitals.
MEDICA.de; Source: University of Michigan