Sunday, November 4, 2007
Bye bye biofilm...maybe?
As we have learned in our microbiology course, the formation of bacterial biofilm is one of the most effective ways of a bacteria to cause an infection in humans. The biofilm is a layer of slime that a colony of bacteria produce to shield themselves from our immune system and from antibiotics. According to a study done by the National Heart, Lung and Blood Institute, 80 percent of infections are caused by the formation of biofilms. If scientists could come up with a way to prevent biofilm formation, it is possible that the number of, and longevity of bacterial infections could be decreased dramatically. Recently, a chemist working at the University of Wisconsin-Madison has begun studies on this subject. However, to understand the techniques of this study properly, a general knowledge of the mechanisms of the generation of a biolfilm is required.
The first step in the creation of a biofilm is when single bacteria attach to their substrate. They do so at first through weak Van der Waals interactions, and then adhere more securely via their attachment structures such as pili. When the accumulation of bacteria is substancial enough, and when the bacteria have anchored sufficiently, the bacteria start acting as a colony and begin to communicate and produce the slime layer, and eventually, the biofilm is created. The first layer of bacteria provide the attachment site for others, and through reproduction, many layers are created and the biofilm mass grows rapidly. One of the most important steps in this process (for the purposes of the study mentioned above) is the communications that lead the colony to begin producing the slime layer, and ultimately the biofilm. The communications occur through a process called quorum sensing.
Quorum sensing is the process in which bacteria control gene expression based on the density of local bacteria. Bacteria have specialized molecules which sense density, and when the density reaches a certain point, the bacteria begin to function as a group, and become a colony which leads to biofilm formation. Quorum sensing is the the focus of the UW chemists studies. Their idea is that if these density sensing molecules can be altered, or tricked, that the formation of colonies would be inhibited, and that the bacteria would continue to exist as single units not acting as a colony. The process of inhibiting the biolfilm formation is called quorum-quenching.
If a successful quorum-quenching drug could be produced, it would greatly benefit the medical community. A quorum-quenching drug, one that does not focus on killing bacteria, would mean that antiobiotics would not have to be the only option for treating bacterial infection. I've had some unpleasant antibiotic experience in the past, and to me, an alternate treatment for bacteria would be a very positive thing. The quorum-quenching drug is still in testing, but hopefully in the near future, this treatment will be available for at least some kids of infections.