Campylobacter jejuni
A Microbial Biorealm page on the genus Campylobacter jejuni
Classification
Higher order taxa
Kingdom: Bacteria, Phylum: Proteobacteria, Class: Epsilon Proteobacteria, Order: Campylobacterales, Family: Campylobacteraceae.
Species
Genus: Campylobacter, Species: C. jejuni.
Description and significance
Campylobacter jejuni is a Gram-negative bacteria that is curved and rod-shaped. It is most commonly found in animal feces, especially in wombat, kangaroo and bird feces. Campylobacter jejuni is a microaerophilic organism, this means that it requires an environment that contains reduced concentration of oxygen (~3-5% of oxygen and ~2-10% of carbon dioxide). Because of this requirement, it is very sensitive to stress in the environment. For example, too much oxygen, acidic condition, heating, and drying(Ref.2). Campylobacter jejuni is the number one cause of foodborne illness in the United States. Therefore, it is very important to sequence its genome to determine its role in these foodborne illnesses and effective treatments can be developed. Campylobacter jejuni is present in high levels in diarrhea stools of an infected individual as well as animal feces. This bacteria can be isolated from humans and animals. Isolation requires special antibiotic-containing media and an environment that contains optimal level of oxygen for microaerophilic organims(Ref.1). Campylobacter jejuni was first categorized in the vibrios. "The new generic term Campylobacter('curved rod' in Greek) was proposed by Sebald and Veron in 1963 on the grounds that the microaerophilic vibrios were different biochemically and serologically from the classical cholera and halophilic vibrios, and had a significantly different deoxyribonucleic acid base-pair ratio from both the latter."(Ref. 7)
Genome structure
The genome of Campylobacter jejuni consists of circular DNA and 1,616,554 nucleotides. It has 1707 genes and 1653 coding proteins. The GC content of Campylobacter jejuni is about 30% and the percentage coding of the bacteria is about 93%. The sequence of Campylobacter jejuni is variable. The eight distribution of variable sequences showed that they can use alternative terminal electron acceptor for oxygen. This represents the diverse life sources for Campylobacter jejuni. According to MLST type, the correlation of clonal complex and distribution of the genes is strong. However, these distribution of genes showed no evidence for their host preferences. Therefore, widespread horizontal gene transfer between clonal complexes is not supported.
Cell structure and metabolism
Campylobacter jejuni is a gram negative bacteria like bacilli. It is microaerophilic and non-fermentive organism. Its structure is similar to most gram negative bacteria. It has one flagellum at one pole or both poles of the cell. The cell contains an outer membrane and an inner membrane with periplasm in between the two membranes. The outer membrane consist of lipopolysaccharide which are endotoxic. Membrane proteins are embedded on the outer membrane surface, they are antigenic and are used for invation of the host. Campylobacter jejuni uses oxygen as its final electron acceptor. This is expected since it is a microaerophilic organism and it gows in its optimal rate with ~5% of oxygen level plus ~10% carbon dioxide. The bacteria is very sensitive to environmental stress such as heating, drying and over concentrated levels of oxygen.
Ecology
Campylobacter jejuni is an interesting bacteria because it resembles some eukaryotic-like system for N-linked protein glycosylation. The disease Camylobacter jejuni caused is known as campylobacer enteritis or gasteroenteritis. The illness leads to severe diarrhea and fecal leukocytes. These symptoms are usually combined with fever, headaches and muscle pain. Children under 5 and young adults are more vulnerable to get the disease more than other groups. Although Campylobacter is the number one cause of foodborne illness, it is the least deadly. The case/fatality ratio is about 1/1000 which is very low.
Pathology
Campylobacter is a bacteria that is found in intestines of many animals and some humans. They cycle through in the intestine environment and lead to diarrhea. Clinical evidence suggests that the site of Campylobacter infection seems to be the ileum and jejunum in the small intestines rather than in the large intestines. Although it is the leading cause of foodborne illness in the United States, Campylobacter can be easily killed by cooking or heating. In most cases, Campylobacter can contaminate water, milk or undercooked meat, especially chicken. It only takes a small amount of bacteria to cause infection. The illness usually lasts 2 to 5 days, and most of these cases will disappear without treatment. However, 25% of these patients are likely to have a relaspse. The early symptom of Campylobacter infection is usually abnormal abdominal pain and is then followed by bloody diarrhea. Other common accompanying symptoms are fever, headache, musle pain, sometimes vomiting and dehydration may occur. Although vomiting and dehydration are not usually prominent, they may be severe enough to lead to death. Complication of Campylobacter infection may also contribute to mortality. For example, deaths have occured in patients who also have cirrhosis, malnutrition, and lymphoma.
Application to Biotechnology
Campylobacter jejuni is not known of producing any useful compounds or enzymes. It is mainly known as a pathogen that causes most foodborne illness in the United States. However, Campylobacter jejuni produce an enzyme called Beta-lactamase that is associated with its antibiotic-resistance, mostly to ampicillin and penicillin. The mechanism of Beta-lactamase in Campylobacter jejuni is still unknown, but effective antibodies are developed to treat Campylobacter jejuni infected illness. For example, the most effective antibody for the treatment is erythromycin. Clinical treatments have suggested that patients treated with erythromycin have significantly reduced the presence of Campylobacter jejuni in their stools, although little is known about its mechanism. Despite erythromycin's effectiveness, moderate erythromycin resistance of Campylobacter jejuni is still present(~5%). However, because the patient is usually recovered without treatment, erythromycin resistance of Campylobacter jejuni is insignificant. Therefore, erythromycin is still the most preferred antibiotics for the treatment of this illness.
Current Research
1) In current research results indicated that ganglioside-like structures gene, such as GM1, which is found on Campylobacter jejuni strains can induce Guillain-Barré Syndrome(GBS). GBS is a postinfectious autoimmune neuropathy which cause the weakness of the limbs, weakness of the respiratory muscles, and areflexia. In a study of rabbits with injection of Campylobacter jejuni lipooligosaccharide(LOS), the rabbits have developed anti-GM1 IgG antibodies and have showed weakness of their limbs. The changes in their peripheral nervous system appear to be identical to that of the GBS patients. Also, another study demonstrats that an antibody Campylobacter jejuni generats called MAb, interact with anti-GM1 IgG in GBS patients can reduce muscle action potentials which explains muscle weakness. In conclusion, Campylobacter jejuni can not only induce GBS, but also interact with antibodies to complicate the illness.
2) This current research is focusing on the effects of environmental stress on the Campylobacter jejuni's survival. The study was done in an vitro cell culture by using Caco-2 cells. The results indicates that when the temperature is elevated, there was a temporary growth arrest and pathogenic potentials. The adhesion and invasion ability had also reduced. However, the bacteria recovered within 24-48hrs. Despite that Campylobacter jejuni is an oxygen denpendent bacteria, oxidative stress did not affect either the growth or the ability of adhesion/invation of the bacteria. However, results indicats that malnutrition was the most powerful stress which reduced bacteria's growths, pathogenic potentials, and adhesion/invasion abilities significantly.
3) Campylobacter jejuni is the major cause of foodborne illness worldwide, its common source of contamination is drinking water. It was thought that Campylobacter jejuni is not able to multiply in water or biofilms, but a recent experiment was done to estimate the suivival ability of Campylobacter jejuni in water and biofilms. By using Propella biofilm reactor and FISH method, the results indicats that the real number of bacteria living in water and biofilms is seriously underestimated.
References
1) Jan M. Hunt, Carlos Abeyta and Tony Tran,"Bacteriological Analytical Manual, 8th Edition, Revision A, 1998 Chapter 7"March 2001[http://www.cfsan.fda.gov/~ebam/bam-7.html,
2) FDA/Center for Food Safety & Applied Nutrition,"Foodborne Pathogenic Microorganisms and Natural Toxins Handbook" January 1992[http://www.cfsan.fda.gov/~mow/chap4.html,
3) Hepworth PJ, Leatherbarrow H, Hart CA, Winstanley C."Use of suppression subtractive hybridisation to extend our knowledge of genome diversity in Campylobacter jejuni" April 2007; 8(1):110 [PubMed][http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17470265&query_hl=1&itool=pubmed_docsum,
4) Karmali MA, Fleming PC,"Campylobacter enteritis" Can Med Assoc J. 1979 June 23; 120(12): 1525–1532.[http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=455209
5) M A Karmali, R M Bannatyne, W Leers, and K Biers,"Erythromycin-resistant Campylobacter jejuni" Can Med Assoc J. 1980 August 23; 123(4): 263–266[http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1704760&pageindex=1
6) E P Wright and M A Knowles,"Beta-lactamase production by Campylobacter jejuni" J Clin Pathol. 1980 September; 33(9): 904–905[http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1146264&pageindex=1#page
7) Vongsavanh Phongsisay, Viraj N. Perera, and Benjamin N. Fry,"Exchange of Lipooligosaccharide Synthesis Genes Creates Potential Guillain-Barré Syndrome-Inducible Strains of Campylobacter jejuni" Infect Immun. 2006 February; 74(2): 1368–1372. doi: 10.1128/IAI.74.2.1368-1372.2006[http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16428786
8) Mihaljevic RR, Sikic M, Klancnik A, Brumini G, Mozina SS, Abram M,"Environmental stress factors affecting survival and virulence of Campylobacter jejuni" 2007 Apr 19; [Epub ahead of print][http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=17512161&ordinalpos=10&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
9) Lehtola MJ, Pitkänen T, Miebach L, Miettinen IT,"Survival of Campylobacter jejuni in potable water biofilms: a comparative study with different detection methods" 2006;54(3):57-61[http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=17037133&ordinalpos=193&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
Edited by LiJie Shi student of Rachel Larsen[lshi@ucsd.edu]
