The "Invincible" Salmonella Biofilm

March 30, 2011
Salmonella is a notorious pathogenic bacterium that is known for poisoning humans and animals and raising the food industry’s annual costs by millions of dollars. Recently, salmonella has proved to be even more dangerous and almost invincible because of its ability to form biofilms.
Biofilms are unique biological structures that occur naturally around the world and are known to be very resistant to man-made antibiotics. A biofilm is defined as an aggregation of minute organisms that adhere together to form large complexes. Just as the definition states, biofilms form when several bacterial cells stick to a surface (Donlan, 2009). Once adhered, the group of cells begins to form probably the most important feature of the aggregation which is the matrix. The matrix not only allows more bacterial cells to accompany the biofilm but more importantly it is the protective backbone that accounts for the biofilm’s remarkable resistancy. The matrix holds all of the biofilm’s components together and makes sure that everything stays organized.
Biofilms can be very troublesome. For example, in research labs, biofilms can contaminate medical equipment and continue to grow to undesirable measures. What is worse is that the amount of antibiotics, or any other treatment, used to get rid of the biofilm would be costly. Water treatment plants sometimes face biofilm problems as well. Biofilms sometimes build up and clog pipes, block filters, and gather more bacteria to contaminate the water even more (Edstrom). These three problems alone can have huge financial consequences. On a larger scale, biofilms have been known to effect ships used for trading and transportation. The biofilms would accumulate around the bottom of the ships along with many other small organisms; this is known as biofouling. As a result of this, there was a 40 percent increase on fuel costs and almost 7 billion dollars were spent annually to control biofouling. (Stanley, 2007)
Salmonella is a bacteria that causes the disease Salmonellosis. It was discovered by a scientist named Salmon and there have been recorded infections of the bacteria for over 100 years. Symptoms of the disease include diarrhea, fever, and abdominal cramps. Salmonellosis usually lasts for about a week but in worst cases a patient may develop stronger cases of the symptoms listed and may even die due to the spread of the bacteria throughout the body. According to the Centers for Disease Control and Prevention, CDC, about 40,000 people are infected with salmonellosis in the United States annually, most of them being young children and the elderly. However, salmonella have been connected to several outbreaks from the past few years with most of them having to deal with food. From 2006 to 2010, Salmonella outbreaks have occurred in peanut butter, tomatoes, shell eggs, and many more foods. As a result these foods had to be recalled by their suppliers causing food industries to lose a lot of capital (CDC, 2010).
Recently, an unusual salmonella case in Norway was inspected by researchers. It was discovered that a particular type of salmonella had been successful in developing in a Norwegian feed and fish meal factory and was even able to last there for several years. Researchers tried to find out why the bacteria were able to live in the factory for so long and why it was so hard to get rid of. Multiple disinfectants were used on the biofilm but were unsuccessful. Eventually, researcher Lene Karine Vestby found that the specific type of salmonella was efficient in producing a biofilm and that it lived longer than the other types of salmonella that were unable to (Science Daily, 2010). Vestby stated that the salmonella biofilms were well protected by the self produced matrix which defended the structure from the many disinfectants used in the factory. Fortunately, Vestby was able to use a couple of treatments to destroy the salmonella biofilm. One was named Vikron S and the other solution consisted of 70 percent ethanol and other substances. Lastly, Vestby tested the effects of furanones on the salmonella. Furanones are organic compounds that are used to interfere with quorum sensing, which is basically the communication between bacterial cells. Her results proved that the furanones were efficient in preventing biofilm development.
Biofilms may be seen as just another scientific subject but they should not be underestimated. Biofilm production made salmonella seem almost invincible at one point but just imagine the other harmful bacteria that can form biofilms and the damage they are capable of. Researchers need to learn more about the development of biofilms in our world and experiment with them in laboratories just as Lene Karine Vestby did in Norway. If this can be accomplished then hopefully many more incidents like the one in Norway one can be prevented.





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