Overview of E.coli

         Kimberly Langille, M.D
         
        E.coli or Escherichia coli  is a bacterium that lives in  the digestive tracts of humans and animals. This type of bacteria is responsible for causing E.coli infection. This occurs usually when consuming contaminated food and water or coming in direct contact with a person or animal who carries the pathogenic form of the bacteria.

                      Structure and Characteristics

        E.coli bacterium is in the form of a bacillus or rod shape. It is classified  under the group of gram negative bacteria. (Public Health Agency of Canada) This group of bacteria are resistant to multiple drugs and increasingly so to most available antibiotics. They have the ability to find new ways to be resistant and pass along genetic material so that other types of bacteria can also become drug resistant. This is a common survival mechanism that E.coli bacteria uses. Colonies of E.coli are around 2 to 3 mm in diameter and can either be red or colourless. The bacterium is a facultative aerobe, meaning it can live under aerobic or anaerobic conditions. (Centers for Disease Control and Prevention)

                                                                Picture of Escherichia Coli

 E.coli illness in Canada and commonality of Pathogenic E.coli illnesses

     
         Between late December 2012 to January 9th 2013, 30 cases of E.coli food borne illnesses  were reported in Canada in the Maritimes and Ontario. E.coli food borne illnesses are not uncommon in the country, as around an average of 440 cases of this infection have been reported annually. (Public Health Agency of Canada)

     E.coli Reproduction

         
            E.coli can reproduce by two processes: binary fission or conjugation. Binary fission is when a single DNA molecule replicates and divides into two identical cells. First, a single DNA molecule replicates. Both copies are separated by the formation of the septum. When the septum is complete, the two copies are divided into identical daughter cells. Conjugation is the transfer of genetic material between two cells. This process is advantageous as it can allow bacteria to adapt to an environment that consistently changes. In conjugation, two different cells line up beside each other. A bridge like structure forms between them called a pilus, which allows DNA from one cell to be transferred to another. The cell receiving the DNA becomes nonidentical from the cell it originally formed from. After conjugation is finished, the cell with new DNA will reproduce through binary fission. (Bailey)

                                 Process of Conjugation                                        Process of Binary Fission

E.coli-Host Relationship and E.coli Survival

        Pathogenic E.coli causes infection in it's host by manipulating their immune response. The bacteria creates a protein called NleH1, which instructs the host immune enzyme IKK-beta to alter specific immune responses. This mechanism allows E.coli to prevent being killed by the host's immune system and prolong it's survival. (Science Daily)

E.coli Symptoms and Virulence

         
            Children are more likely to develop symptoms of E.coli infection than adults. Common symptoms of the infection include severe stomach cramps, bloody diarrhea and nausea, along with vomiting. Although bloody diarrhea is common in confirmed cases of E.coli infection, it is possible that the infection can be a cause of non bloody diarrhea. Most individuals who contract E.coli infection recover fully in 7 to 10 days. Around 5 to 10 percent who receive the illness will develop hemolytic uremic syndrome (HUS), a type of kidney failure and blood disorder which can result in death.

  Transmission

             Pathogenic E.coli can be transmitted through eating contaminated food. Examples of food which can cause E.coli infection are improperly cooked beef, uncooked vegetables and unpasteurized milk. It can also be transferred from human to human.

           Prevention

             Proper hygiene along with safe food handling practices is important for preventing E.coli infection. Handwashing is one of the best ways; along with making sure that food is cooked enough in order to destroy the bacteria. Other tips include:

- Washing fresh fruits or vegetables before eating them.
- Refrigerating perishable foods within two hours of cooking.

           Treatment

         
            Generally, it is best to allow the disease to run it's course. Treatment for those who have  E.coli infection is to drink plenty of water in order to replace the body fluids which were lost through vomiting and diarrhea, and to prevent dehydration. Antibiotics are not used for treating the illness as they increase the risk of one developing HUS.

(Public Health Agency of Canada)

                                                                           E.coli Benefits

          The bacterium is capable of producing sugar modified proteins called glycoproteins. Glycoproteins can allow for production of cheaper and faster prescription drugs. This proteins in medications can also inhibit cancer cells from multiplying. (Medical News Today)

Works Cited

Bailey, Regina. "Binary Fission in Prokaryotes." About.com Biology. About.com, n.d. Web. 27 Oct. 2013.

Centers for Disease Control and Prevention. "Gram-negative Bacteria Infections in Healthcare Settings." Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 17 Jan. 2011. Web. 27 Oct. 2013.

Medical News Today. "What Is E.coli? (Escherichia Coli)." Medical News Today. MediLexicon International, 21 May 2013. Web. 27 Oct. 2013.

Public Health Agency of Canada. "Escherichia Coli." Escherichia Coli. Public Health Agency of Canada, 30 Apr. 2012. Web. 27 Oct. 2013.

Public Health Agency of Canada. "Public Health Notice: E. Coli O157:H7 Illnesses in the Maritimes and Ontario." Public Health Agency of Canada. N.p., 7 Feb. 2013. Web. 27 Oct. 2013.

Science Daily. "How Pathogenic E. Coli Bacterium Causes Illness." ScienceDaily. ScienceDaily, 15 Mar. 2011. Web. 27 Oct. 2013.