User:KeinsleyM
A Microbial Biorealm page on the genus KeinsleyM
Classification
Higher order taxa
Domain: Bacteria; Phylum: Proteobacteria; Class: Epsilon Protobacteria; Order: Camplyobacterales; Family: Campylobacteraceae [Others may be used. Use NCBI link to find]
Species
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NCBI: [1] |
Genus: Campylobacter; Species: C. jejuni
Description and significance
Campylobacter jejuni is a gram-negative bacterium that can be isolated from cattle, chickens, birds, flies and non-chlorinated water. This rod shaped bacterium is generally isolated from the feces of the animals listed earlier and the most pathogenic form is transmitted from chickens. (2)
This motile bacterium is a major cause of gastroenteritis, causing diarrhea, nausea, headaches, and other muscle pains. The bacterium is usually ingested after eating raw or undercooked chicken. (2)
Genome structure
C. jejuni are slender rods with a circular chromosome containing 1,641,481 base pairs encoding 1,654 proteins and 54 RNA species. 30.6% of the base pairs are G+C. In order to survive, C. jejuni has hypervariable sequences found in genes encoding synthesis or modification of surface structures. It is believed that in order for Campylobacter jejuni to survive, it must have these hypervariable sequences in the genome as they have a high rate of variation. This genome does not contain any insertion sequences, phage-associated sequences, or repeat sequences. (3)
Cell structure and metabolism
Campylobacter jejuni are gram-negative, rod shaped, motile bacteria. They contain a flagellum at one end of their spiral structure. They have corkscrew motility and joing to form zigzag patterns. (6) C. jejuni test positive for nitrate reduction, oxidase, catalase, and MacConkey’s agar. It is also able to grow at high temperatures and low temperatures. Room temperature conditions do not promote growth. With minimal oxygen and a moist habitat, they can survive nearly a month. It uses carbohydrates found inside the gastrointestinal tract to gain energy for growth. (4)
Ecology
C. jejuni is most often found infecting cattle, chickens, birds and flies. It has been found in non-chlorinated water as well. Generally, isolation of this bacterium is done using the feces of these animals. This bacterium is highly infective, explaining why so many livestock types are infected. By residing in untreated water sources, it easily infects livestock. It does not generally contribute to its environment in water or animals, but causes disease in humans. (6)
Pathology
By residing in untreated water and animals frequently consumed by humans, C. jejuni infects humans by infecting their gastrointestinal tract. Eating raw or uncooked poultry and beef can cause these infections along with consumption of untreated water and unpasteurized milk. To cause infection, as few as 400 bacterial cells must be consumed, although this number may vary on the susceptibility of the human. (6)
The bacterium’s ability to infect is determined by the motility, chemotaxis and the flagella that are used to attach to the intestinal epithelial cells. Other virulence determinants are host cell invasion, toxin production, epithelial disruption, and inflammation. Recent studies have shown it to be antimicrobial-resistant causing treatment to become more difficult. (7)
C. jejuni is a leading cause of gastroenteritis in the United States and underdeveloped countries. It causes mild to sever diarrhea, vomiting, nausea, headaches, and muscle weakness. The symptoms can last days or even weeks depending on the status of the immune system of the infected person and the amount of cells ingested. More serious cases have caused meningitis, pneumonia, and resulted in some miscarriages. (6)
Current Research and or Application to Biotechnology
In recent research of C. jejuni, researchers have shown that it must infect the mucus layer of the intestinal epithelium. This layer in humans and chickens can influence the virulence of the bacterium. They are still unsure of the specific components of the epithelial layer that contribute to the increased virulence. (8)
Stahl has also recently shown that the utilization of L-fucose in the gastrointestinal system helps Campylobacter jejuni grow in the gut. C. jejuni utilizes other intestinal carbohydrates, most of which are released from the mucin glycoproteins in the mucus membrane. This allows the bacterium to anchor into the gut and provides a source of food for it to grow. They have also shown that in the presence of L-fucose and mutations of different C. jejuni phenotypes, growth is facilitated in the pig model, but not in a poultry model, leading to increased research about this metabolic pathway to explain the differences. (9)
Other research has also shown that C. jejuni has been able to become more acid tolerance in the intestinal tract if incubated with amoebae. It was able to survive an environment of pH 2 for 5 hours and pH 4 for 10 hours. At pH 5, the motility of the bacteria triggered motility and even internalization of the amoebae. It is hypothesized that the amoebae may act as a protective host against harsh conditions that C. jejuni may encounter in the intestinal system. This research is still being conducted to determine if this hypothesis is plausible. (10)
References
2. FDA. "Foodboorne Illness: Camylobacter Jejuni." Bad Bug Book. BBB: Foodborne Pathogenic Microorganisms and Natural Toxins Handbook. U.S. Food and Drug Administration, 04 Mar. 2012. Web. 07 May 2012. <http://www.fda.gov/food/foodsafety/foodborneillness/foodborneillnessfoodbornepathogensnaturaltoxins/badbugbook/ucm070024.htm>.
3. Parkhill, J., B.W. Wren, K. Mungall, J. M. Ketley, and C. Churcher. "The Genome Sequence of the Food-borne Pathogen Campylobacter Jejuni Reveals Hypervariable Sequences." Nature 403 (2000): 665-68. Nature.com. Nature Publishing Group, 10 Feb. 2000. Web. 07 May 2012. <http://www.nature.com/nature/journal/v403/n6770/abs/403665a0.html>.
4. Barrett, T.J., C.M. Patton and G.K. Morris. 1988. Differentiation of Campylobacter species using phenotypic characterization. Lab. Med. 19:96-102.
6. FDA. "Laboratory Methods." Bacteriological Analytical Manual. U.S. Food and Drug Administration, 2001. BAM: Campylobacter. 08 Mar. 2001. Web. 09 May 2012. <http://www.fda.gov/Food/ScienceResearch/LaboratoryMethods/BacteriologicalAnalyticalManualBAM/UCM072616>.
7. Altekruse SF, Stern NJ, Fields PI, Swerdlow DL. Campylobacter jejuni–an emerging foodborne pathogen. Emerg Infect Dis. 1999;5:28–35.
8. Byrne CM, Clyne M, Bourke B (2007) Campylobacter jejuni adhere to and invade chicken intestinal epithelial cells in vitro. Microbiology 153:561–569.
9. Stahl, Martin, Lorna Friis, Harald Nothaft, and Xin Liu. "L-Fucose Utilization Provides Campylobacter Jejuni with a Competitive Advantage." L-Fucose Utilization Provides Campylobacter Jejuni with a Competitive Advantage. Procedings of Th National Academy of Sciences of the United States of America, 11 Apr. 2011. Web. 09 May 2012. <http://www.pnas.org/content/108/17/7194.short>.
10. Axelsson-Olsson, Diana, Lovisa Svensson, Jenny Olofsson, and Paulo Salomon. "American Society for Microbiology Applied and Environmental Microbiology." Increase in Acid Tolerance of Campylobacter Jejuni through Coincubation with Amoebae. American Society for Microbiology, May 2010. Web. 09 May 2012. <http://aem.asm.org/content/76/13/4194.short>.
Edited by student of Dr. Lynn M Bedard, DePauw University http://www.depauw.edu
