A biofilm is a community of microorganisms in a self-developed polymeric matrix, which allows them to attach to each other and various surfaces. A biofilm can form on living or non-living surfaces and are found commonly on catheters, showers, plaque on teeth, water pipes, lungs, and various types of medical equipment. Wherever you find a combination of moisture, nutrients, and a surface, you are likely to find a biofilm. An estimated 80 percent of all human bacterial infections are caused by biofilms.
Biofilm begin to form when a free floating bacteria adheres itself to a surface and forms a conditioning layer. An electrical charge builds on the surface and becomes increasingly attractive to bacteria carrying an opposite charge. The electrostatic forces are weak and reversible at this stage and the microorganisms are easily removed and killed by mild cleaners and sanitizers. If the bacteria remain after this stage a firm attachment phase begins. A sticky matrix of sugars, proteins, and genetic material called extracellular polysaccharide substance (EPS) develops surrounding the cells within the biofilm. This slime coat creates most of the biofilms mass, serves as protection, prevents detection, and facilitates the attachment of other organisms into the colony.
A fully formed biofilm now allows the individual bacterial cells to communicate with each other via quorum sensing. This activity helps cells pass information about their neighbors and surrounding environment to one another. Quorum sensing is known to cause changes of behavior in cells and may provide insight into why cells decide to detach from biofilms.
Dispersal of cells from within the biofilm allows them to spread, colonize and rapidly multiply on other surfaces. It is not yet fully understood how detachment occurs after the cells have firmly attached and immobilized, but it can be coordinated in response to environmental shifts such as increased or decreased nutrient availability, or changes in temperature. Bacteria in these communities are more resistant to antibiotics and disinfectants than individual bacteria. When these bacteria detach from a biofilm causing infection in the body, the matrix that prevents detection is no longer surrounding the detached cells. The immune system suddenly becomes aware of their presence and may trigger an inflammatory response that leads to heightened disease symptoms. The dispersed bacteria are usually susceptible to antibiotics once again.
The antibiotic resistance capabilities in biofilm are different from plasmids, transposons, and mutations that induce an innate immune response by individual bacterial cells. In biofilms, resistance seems to depend on multicellular...