Entamoeba coli

大腸アメーバ

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1. a pass between mountain peaks (同)gap

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1. (山脈の)鞍部(あんぶ),山あい

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/14 15:11:08」(JST)

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This article is about the protozoal parasite Entamoeba coli. For the bacterium with the species abbreviation E. coli, see Escherichia coli.

Entamoeba coli
Entamoeba coli cyst
Scientific classification
Domain:	Eukaryota
Phylum:	Amoebozoa
Class:	Archamoebae
Genus:	Entamoeba
Species:	E. coli
Binomial name
Entamoeba coli

Entamoeba coli is a non-pathogenic species of Entamoeba that frequently exists as a commensal parasite in the human gastrointestinal tract. E. coli (not to be confused with the bacterium Escherichia coli) is important in medicine because it can be confused during microscopic examination of stained stool specimens with the pathogenic Entamoeba histolytica. This amoeba does not move much by the use of its pseudopod, and creates a "sur place (non-progressive) movement" inside the large intestine. Usually, the amoeba is immobile, and keeps its round shape. This amoeba, in its trophozoite stage, is only visible in fresh, unfixed stool specimens. Sometimes the Entamoeba coli have parasites as well. One is the fungus Sphaerita spp. This fungus lives in the cytoplasm of the E. coli. While this differentiation is typically done by visual examination of the parasitic cysts via light microscopy, new methods using molecular biology techniques have been developed. The scientific name of the amoeba, E. coli, is often mistaken for the bacterium, Escherichia coli. Unlike, the bacterium, the amoeba is mostly harmless, and does not cause as many intestinal problems like some of the strains of E. coli. Some of these harmful strains are inside raw or uncooked meat that is consumed. For example, the bacterium, E. coli O157:H7, which can cause illness, and even death, if eaten. To make the naming of these organisms less confusing, "alternate contractions" are used to name the species for the purpose making the naming easier; for example, using Esch. coli and Ent. coli for the bacterium and amoeba, instead of using E. coli for both.

Common lifecycle of non-pathogen parasites.

Clinical significance

Entamoeba coli cyst with more than 4 nuclei

The presence of E.coli is not cause in and of itself to seek treatment as it is considered harmless. However, when a person becomes infected with this benign entamoeba, other pathogenic organisms may have been introduced as well, and these other pathogens might cause infection or illness.

Morphology

Stages of the Entamoeba coli parasite.

Entamoeba species all come in monogenetic forms, or having one generation lifecycles. E. coli has "three distinct morphological forms exist airing the life cycle-Trophozoite, Pre-cystic stage and Cystic stage." This lifecycle gives raise to the general way of how Entamoeba species forms. This parasite has one large nucleus with a thick membrane surrounding the nucleus. There are many chromatin inside the nucleus, and one large, irregular-shaped karyosome. The chromatin is clumped, and uneven in disperse inside the nucleus. The parasite forms by binary fission like most Entamoeba spp. The mature cyst is the infective stage, and is known to survive longer than those of E. histolytica. The cysts can survive three to four mouths outside the host’s body after desiccation. The cysts cause infection by consuming contaminated food and drinks like waste water. Sometimes insects and rodents carry the parasite to cause infection in the food and drinks. Excystation happens once the cysts are ingested, and travel to the large intestine.

Diagnosis

E. Coli trophozoites can be distinguished by their wide and tapered pseudopodia. They are often mistaken for E. histolytica due to their overlap in size. The cysts are distinguished by noticing the eight nuclei found in the mature form. To diagnosis for E. coli, a stool sample is usually tested. This is the best method to check to see if the parasite is E. coli and not E. histolytica. This usually involves checking the cysts for the size, shape, and the number of nuclei. E. coli has cysts in size to 10 to 35 micrometers, the shape is irregular, oval with a shell-like appearance that is more uniformed compared to E. histolytica, and has up to eight nuclei in the cyst compared to the four nuclei of E. histolytica. To the untrained eye of by inexperienced microbiologists, "tetranucleate cysts of Entamoeba coli can be mistaken for mature cysts of Entamoeba histolytica" Often " a tetranucleate Entamoeba coli cyst is larger than a mature cyst of Entamoeba histolytica, can be variable in shape, and has nuclear peripheral chromatin and karyosome composed of irregular granules" in this matter of comparison. To make a diagnosis for any Entamoeba species, usually a wet mount is created "by finding the characteristic cysts in an iodine stained, formol-ether concentration method or by detecting the characteristic trophozoites in a wet preparation or a permanent stained preparation" to see what they may look like. Also, these stains of trichrome can be used to mount the cysts of any Entamoeba spp. Other tests can be used to diagnosis for Entamoeba spp. These tests involve the use of laboratory methods. Some of these laboratory tests include: the use of light microscopy, culture methods, isoenzyme analysis, antibody detection tests, antigen detection tests, immunochromatographic assays, and DNA-based diagnostic tests. Some uses of microscopy also involve the use of transmission electron microscopy and scanning electron microscopy. Usually, the cysts are freeze fractured to insure that the samples are easier to look at to compare Entamoeba spp. The DNA-based diagnostic tests include the use of DNA extraction, PCR, microarrays, and typing methods.For example, one DNA-based diagnostic test that is changing how Entamoeba spp. is being diagnosis faster and more accurate is by using the "Reverse Line Hybridization Assay" test. This test main purpose is to detect and different Entamoeba spp. in stool samples in order to find the causative agent of amoebic dysentery, E. histolytica. This test involves the use of gene sequencing, and seeing what different genomes each Entamoeba spp. has to help detect the deadly E. histolytica.

Pathology

E. coli are mostly harmless parasites, and do not cause harm to the host. However, there have been cases of internal bleeding. Usually, the cytoplasm of the E. coli "does not contain red blood cells, except in the rare case of patients with intestinal hemorrhage" that leads to blood in the stools of these patients. This may lead to intestinal lesions. Other problems that E. coli causes are usually result from having too many in the large intestine. For example, large populations of E. coli may lead to "dyspepsia, hyperacidity, gastritis, and indigestion"; these are common problems of most intestinal parasites.

Treatment

There is generally no need to treat for E. coli, due to the rarity of this parasite becoming infectious. In one exceptional situation, E. coli was found to be infectious: in northern Europe, stool samples and electron microscopy revealed large populations of the amoeba within a group of patients with persistent diarrhea. Some types of treatments may need to be used due to large populations. Some arsenical compounds are shown to treat the trophozoite stage, like carbarsone. Other compounds used to treat large populations of E. coli are Diloxanide furoate, and this usually is used in antiamebic therapy.

See also

• Amoebiasis

References

Further reading

• Hashmey R, Genta RM, White Jr (1997). "Parasites and Diarrhea. I: Protozoans and Diarrhea". Journal of travel medicine 4 (1): 17–31. doi:10.1111/j.1708-8305.1997.tb00769.x. PMID 9815473. 

UpToDate Contents

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• 1. 非病原性腸内原虫 nonpathogenic enteric protozoa

English Journal

• Study of the gastrointestinal parasitic fauna of captive non-human primates (Macaca fascicularis).

• Zanzani SA1, Gazzonis AL2, Epis S3, Manfredi MT4.
• Parasitology research.Parasitol Res.2015 Sep 15. [Epub ahead of print]
• The aim of this study was to examine helminths and protozoans in cynomolgus macaques (Macaca fascicularis) imported from registered breeding facilities in China and their relation to health risks for non-human primate handlers in biomedical research centers and in breeding facilities. Fresh fecal sa
• PMID 26374536

• Novel hemagglutinating, hemolytic and cytotoxic activities of the intermediate subunit of Entamoeba histolytica lectin.

• Kato K1, Yahata K2, Gopal Dhoubhadel B1,3, Fujii Y4, Tachibana H5.
• Scientific reports.Sci Rep.2015 Sep 10;5:13901. doi: 10.1038/srep13901.
• Galactose and N-acetyl-D-galactosamine (Gal/GalNAc) inhibitable lectin of Entamoeba histolytica, a common protozoan parasite, has roles in pathogenicity and induction of protective immunity in mouse models of amoebiasis. The lectin consists of heavy (Hgl), light (Lgl), and intermediate (Igl) subunit
• PMID 26354528

• Spectrum of enteropathogens detected by the FilmArray GI Panel in a multicentre study of community-acquired gastroenteritis.

• Spina A1, Kerr KG2, Cormican M3, Barbut F4, Eigentler A5, Zerva L6, Tassios P6, Popescu GA7, Rafila A7, Eerola E8, Batista J9, Maass M10, Aschbacher R11, Olsen KE12, Allerberger F13.
• Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases.Clin Microbiol Infect.2015 Aug;21(8):719-28. doi: 10.1016/j.cmi.2015.04.007. Epub 2015 Apr 20.
• The European, multicentre, quarterly point-prevalence study of community-acquired diarrhoea (EUCODI) analysed stool samples received at ten participating clinical microbiology laboratories (Austria, Finland, France, Germany, Greece, Ireland, Italy, Portugal, Romania, and the UK) in 2014. On four spe
• PMID 25908431

Japanese Journal

• Structural and mutational analysis of amino acid residues involved in ATP specificity of Escherichia coli acetate kinase(ENZYMOLOGY, PROTEIN ENGINEERING, AND ENZYME TECHNOLOGY)

• Yoshioka Aya,Murata Kousaku,Kawai Shigeyuki
• Journal of bioscience and bioengineering 118(5), 502-507, 2014-11
• … Acetate kinase (AK) generally utilizes ATP as a phosphoryl donor, but AK from Entamoeba histolytica (PPi-ehiAK) uses pyrophosphate (PPi), not ATP, and is PPi-specific. … Each candidate residue in Escherichia coli ATP-specific AK (ATP-ecoAK), which is unable to use PPi, was substituted with the respective PPi-ehiAK amino acid residue. …
• NAID 110009894832

• Serological Surveillance Development for Tropical Infectious Diseases Using Simultaneous Microsphere-Based Multiplex Assays and Finite Mixture Models

• Fujii Yoshito,Kaneko Satoshi,Nzou Samson Muuo,Mwau Matilu,Njenga Sammy M.,Tanigawa Chihiro,Kimotho James,Mwangi Anne Wanjiru,Kiche Ibrahim,Matsumoto Sohkichi,Niki Mamiko,Osada-Oka Mayuko,Ichinose Yoshio,Inoue Manabu,Itoh Makoto,Tachibana Hiroshi,Ishii Kazunari,Tsuboi Takafumi,Yoshida Lay Myint,Mondal Dinesh,Haque Rashidul,Hamano Shinjiro,Changoma Mwatasa,Hoshi Tomonori,Kamo Ken-ichi,Karama Mohamed,Miura Masashi,Hirayama Kenji
• PLoS Neglected Tropical Diseases 8(7), e3040, 2014-07-31
• … To establish a simple and practical seroprevalence detection system, we developed a microsphere-based multiplex immunoassay system and evaluated utility using samples obtained in Kenya.Methods:We developed a microsphere-based immuno-assay system to simultaneously measure the individual levels of plasma antibody (IgG) against 8 antigens derived from 6 pathogens: Entamoeba histolytica (C-IgL), Leishmania donovani (KRP42), Toxoplasma gondii (SAG1), Wuchereria bancrofti (SXP1), HIV (gag, gp120 and gp41), and Vibrio cholerae (cholera toxin). …
• NAID 120005477034

• 寄生虫陽性率の経年的変化と寄生虫検査継続意義

• 小松 悦子,福田 弥生,鵜原 日登美,遠田 栄一,石坂 裕子,山門 實
• 人間ドック (Ningen Dock) 28(4), 641-645, 2013
• <B>目的：</B>三井記念病院総合健診センター（以下，当センター）における寄生虫陽性率の経年的変化を検討し，今後の人間ドックにおける寄生虫検査の継続意義について考察した．<B>方法：</B>対象は1994年8月から2012年3月までに当センターを受診した1泊人間ドック受診者4,673名で，虫卵の検出法はホルマリン・エーテル沈殿集卵法で行った．この他 …
• NAID 130003396581

Related Links

• Entamoeba coli - Ministry of Health,Labour and Welfare ...

大腸アメーバ "嚢子" 世界に広く分布している。大腸に寄生するが病原性はない。赤痢アメーバとの鑑別が重要である。生活史上、栄養型と嚢子の2期がある。 形態： 栄養型は15～50μmのアメーバ状で緩慢に運動し、しばしば細菌の貪食 ...

• Entamoeba coli - definition of Entamoeba coli by Medical ...

Entamoeba coli, a common nonpathogenic amebic parasite found in the intestines of humans and other mammals. It is similar to and sometimes confused with E. histolytica, the causal agent of amebic dysentery. However, E. coli organisms tend to be slightly larger, have more pseudopods, and be sluggish in movement.

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