32-490: E. bangladeshi E. bovis E. chattoni E. coli E. dispar E. ecuadoriensis E. equi E. gingivalis E. hartmanni E. histolytica E. insolita E. invadens E. moshkovskii E. muris E. nuttalli E. polecki E. ranarum E. struthionis E. suis E. terrapinae Entamoeba is a genus of Amoebozoa found as internal parasites or commensals of animals. In 1875, Fedor Lösch described
64-452: A process called encystation. The number of nuclei in the cyst varies from 1 to 8 among species and is one of the characteristics used to tell species apart. Of the species already mentioned, Entamoeba coli forms cysts with 8 nuclei while the others form tetra-nucleated cysts. Since E. histolytica does not form cysts in vitro in the absence of bacteria, it is not possible to study the differentiation process in detail in that species. Instead
96-422: 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
128-435: 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 . E. coli are mostly harmless parasites, and do not cause harm to
160-400: Is found in the mouth inside the gingival pocket biofilm near the base of the teeth, and in periodontal pockets. Entamoeba gingivalis is found in 95% of people with gum disease and rarely in people with healthy gums. Cyst formation is not present; therefore transmission is direct from one person to another by kissing, or by sharing eating utensils. Only the trophozoites are formed and
192-436: 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
224-462: 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
256-414: Is the infective stage, and is known to survive longer than those of E. histolytica . The cysts can survive three to four months 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
288-441: 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,
320-673: The "midwife") to complete the fission. He writes: They also reported a similar behavior in Dictyostelium . Since E. histolytica does not form cysts in the absence of bacteria, E. invadens has become used as a model for encystation studies as it will form cysts under axenic growth conditions, which simplifies analysis. After inducing encystation in E. invadens , DNA replication increases initially and then slows down. On completion of encystation, predominantly tetra-nucleate cysts are formed along with some uni-, bi- and tri-nucleate cysts. Uninucleated trophozoites convert into cysts in
352-459: The amoeba Entamoeba gingivalis in the infected periodontal crevices, besides moving, consists in feeding on the nucleus of white blood cells. The amoeba penetrates into the cytoplasm to reach the nucleus and literally suctions its contents via the negative pressure of the pseudopod. The food so gulped down is gradually digested inside the endoplasm. Phagocytosis can sometimes continue for more than 20 polynuclear neutrophil nuclei. This activity leaves
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#1732765413500384-425: 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 as some strains of the E. coli bacterium. 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
416-515: The bacterium and amoeba, instead of using E. coli for both. 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. Entamoeba species all come in monogenetic forms, or having one generation lifecycles. E. coli has "three distinct morphological forms exist airing
448-577: 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
480-479: The cysts for the size, shape, and the number of nuclei. E. coli has cysts in size up 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 an inexperienced microbiologists, "tetranucleate cysts of Entamoeba coli can be mistaken for mature cysts of Entamoeba histolytica " Often "
512-465: The differentiation process is studied using E. invadens , a reptilian parasite that causes a very similar disease to E. histolytica and which can be induced to encyst in vitro . Until recently there was no genetic transfection vector available for this organism and detailed study at the cellular level was not possible. However, recently a transfection vector was developed and the transfection conditions for E. invadens were optimised which should enhance
544-418: The eukaryotic meiosis-specific recombination accessory factor (heterodimer) Hop2-Mnd1. These processes are central to meiotic recombination, suggesting that E. histolytica undergoes meiosis. Studies of E. invadens found that, during the conversion from the tetraploid uninucleate trophozoite to the tetranucleate cyst, homologous recombination is enhanced. Expression of genes with functions related to
576-469: The first proven case of amoebic dysentery in St. Petersburg, Russia. He referred to the amoeba he observed microscopically as Amoeba coli ; however, it is not clear whether he was using this as a descriptive term or intended it as a formal taxonomic name. The genus Entamoeba was defined by Casagrandi and Barbagallo for the species Entamoeba coli , which is known to be a commensal organism. Lösch's organism
608-495: The free-living amoebo-flagellates of the genus Mastigamoeba and related genera. Certain other genera of symbiotic amoebae, such as Endamoeba , might prove to be synonyms of Entamoeba but this is still unclear. Studying Entamoeba invadens , David Biron of the Weizmann Institute of Science and coworkers found that about one third of the cells are unable to separate unaided and recruit a neighboring amoeba (dubbed
640-568: 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. There
672-458: The large intestine. 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 diagnose 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
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#1732765413500704-447: The late 1950s, and Entamoeba has stayed 'stable' ever since. Several species are found in humans and animals. Entamoeba histolytica is the pathogen responsible for invasive ' amoebiasis ' (which includes amoebic dysentery and amoebic liver abscesses ). Others such as Entamoeba coli (not to be confused with Escherichia coli ) and Entamoeba dispar are harmless. With the exception of Entamoeba gingivalis , which lives in
736-463: The life cycle-Trophozoite, Pre-cystic stage and Cystic stage". This lifecycle gives rise to the general way of how Entamoeba species form. 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
768-510: The life cycle. Many other species of Entamoeba have been described, and it is likely that many others remain to be found. Entamoeba cells are small, with a single nucleus and typically a single lobose pseudopod taking the form of a clear anterior bulge. They have a simple life cycle. The trophozoite (feeding-dividing form) is approximately 10-20 μm in diameter and feeds primarily on bacteria. It divides by simple binary fission to form two smaller daughter cells. Almost all species form cysts,
800-438: The major steps of meiotic recombination also increased during encystations. These findings in E. invadens , combined with evidence from studies of E. histolytica indicate the presence of meiosis in the Entamoeba . 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
832-428: The mouth, and E. moshkovskii , which is frequently isolated from river and lake sediments, all Entamoeba species are found in the intestines of the animals they infect. Entamoeba invadens is a species that can cause a disease similar to E. histolytica but in reptiles. In contrast to other species, E. invadens forms cysts in vitro in the absence of bacteria and is used as a model system to study this aspect of
864-574: The research possibilities at the molecular level of the differentiation process. In sexually reproducing eukaryotes , homologous recombination (HR) ordinarily occurs during meiosis . The meiosis-specific recombinase , Dmc1 , is required for efficient meiotic HR, and Dmc1 is expressed in E. histolytica . The purified Dmc1 from E. histolytica forms presynaptic filaments and catalyzes ATP -dependent homologous DNA pairing and DNA strand exchange over at least several thousand base pairs . The DNA pairing and strand exchange reactions are enhanced by
896-518: The size is usually 20 micrometers to 150 micrometers in diameter. Entamoeba gingivalis have pseudopodia that allow them to move quickly and phagocytise the nucleus of polynuclear neutrophils by exonucleophagy in periodontal disease. Their spheroid nucleus is 2 micrometers to 4 micrometers in diameter and contains a small central endosome . There are numerous food vacuoles , which consists mostly of phagocitised PMN nucleus, blood cells, and bacteria. It also causes pyorrhoea. The main activity of
928-614: The stage involved in transmission (the exception is Entamoeba gingivalis ). Depending on the species, these can have one, four or eight nuclei and are variable in size; these characteristics help in species identification. Entamoeba belongs to the Archamoebae , which like many other anaerobic eukaryotes have reduced mitochondria . This group also includes Endolimax and Iodamoeba , which also live in animal intestines and are similar in appearance to Entamoeba , although this may partly be due to convergence. Also in this group are
960-426: The trophozoite stage, like carbarsone . Other compounds used to treat large populations of E. coli include diloxanide furoate , and this usually is used in antiamebic therapy. Entamoeba gingivalis Entamoeba gingivalis is an opportunistic Amoebozoa (reported by some as an effect of disease; not a cause [hence status as a commensal ]) and is the first amoeba in humans to be described. It
992-429: 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
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1024-500: Was renamed Entamoeba histolytica by Fritz Schaudinn in 1903; he later died, in 1906, from a self-inflicted infection when studying this amoeba. For a time during the first half of the 20th century the entire genus Entamoeba was transferred to Endamoeba , a genus of amoebas infecting invertebrates about which little is known. This move was reversed by the International Commission on Zoological Nomenclature in
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