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Entamoeba histolytica
Published in Peter D. Walzer, Robert M. Genta, Parasitic Infections in the Compromised Host, 2020
William A. Petri, Jonathan I. Ravdin
Amebas from clinical isolates can be maintained in long-term culture by adapting them to monoxenic culture with a single bacterial or trypanosomatid associate. Entamoeba coli and E. hartmanni must be maintained in monoxenic culture, as they have never been grown successfully in axenic culture (68). Axenic culture is the ideal medium in which to maintain E. histolytica for scientific study. Diamond, in 1961, first described axenic cultivation of E. histolytica (11). The medium currently in use is TYI-S-33 (trypticase-yeast extract-ironserum) (68,70). The source of the trypticase, which is a pancreatic digest of casein, is essential for success in cultivation, as most commercial casein digests will not support the growth of Entamoeba (68). The digest currently used in TYI-S-33 is casein digest peptone (catalog #97023, BBL Microbiology Systems, Cockeysville, MD). A major disadvantage of axenic culture is the inability of the parasite to encyst (68).
Cultivation of Entamoeba Histolytica
Published in Roberto R. Kretschmer, Amebiasis: Infection and Disease by Entamoeba histolytica, 2020
Entamoeba histolytica was first cultured in 1925,2 50 years after its discovery in 1875. The earlier claim by Cutler has never been substantiated by other investigators,3 and is today discredited.4,5 Cultivation was accomplished in the presence of a human enteric flora of unknown composition (xenic culture).2 Five years after this momentous event, cultivation of the ameba in the presence of a single identified species of bacteria was reported (monoxenic culture).5 Growth in the absence of all other metabolizing cells (axenic culture) was described in 1961,6 36 years after the first successful culture of this parasite.
In Vitro Studies on Chemical Regulation of Gametangial Formation in Bryophytes
Published in R. N. Chopra, Satish C. Bhatla, Bryophyte Development: Physiology and Biochemistry, 2019
In recent years considerable work has been done on chemical regulation of sexual reproduction in bryophytes grown in vitro. Although the conditions of growth in axenic cultures are in some ways far from natural, it is hoped that ultimately the data obtained in artificial conditions will be helpful in understanding the way sexual reproduction is regulated in vivo. The significance of responses to applied chemicals has its basis in the fact that all the major growth regulators have been reported in bryophytes.
Identification of a growth factor required for culturing specific fastidious oral bacteria
Published in Journal of Oral Microbiology, 2023
Pallavi Murugkar, Eric Dimise, Eric Stewart, Stéphane N. Viala, Jon Clardy, Floyd E. Dewhirst, Kim Lewis
P. pasteri is one of the 12 most abundant bacteria in the oral cavity and the second most abundant in saliva [13]. In several studies examining the salivary microbiome or oral rinses, the relative abundance of P. pasteri was positively associated with oral health while lower relative abundance was associated with periodontal disease [37–39], Sjogren’s syndrome [40], and oral squamous cell carcinoma [41]. In contrast to its role in oral health, in cystic fibrosis, it is associated with a decline in lung function [42]. P. pasteri is not only abundant in all nine of the oral sites studied in human microbiome [13] but it is also present in the vaginal microbiome where it has been isolated and a genome sequence produced (P. pasteri strain KA00683 Table S1) [43]. Considering its oral abundance, oral health association, and possible association with disease in other body sites, P. pasteri appears to be an important bacterial species that has been remarkably understudied. Future studies of this species should be greatly facilitated by knowing that its isolation and axenic culture depend on, or are enhanced by, culture in media containing DHNA.
Inhibitory effect of Tunceli garlic (Allium tuncelianum) on blastocystis subtype 3 grown in vitro
Published in Expert Opinion on Orphan Drugs, 2020
Mehmet Aykur, Emrah Karakavuk, Muhammet Karakavuk, Mesut Akıl, Hüseyin Can, Mert Döşkaya, Yüksel Gürüz, Hande Dağcı
To date, many in vitro studies have been performed on the effects of drugs against Blastocystis using various types of xenic cultures [49–51]. In this study, all Blastocystis subtype 3 used were isolated from patients and cultured with the associated bacteria. The condition of these strains’ growth in this medium resemble more like to their normal habitat in the gut. On the other hand, there are some problems when using axenic cultures for in vitro drug testing of Blastocystis isolates. Axenic cultures are not practical for clinical laboratories as they require a lot of time and are expensive. Also, eliminating the bacteria that act as a food source for Blastocystis can alter the properties of the culture. On the other hand, Blastocystis can be grown in less than 1 week in xenic culture. As a result of eliminating the necessary bacteria for the growth of Blastocystis or a applies equally to the axenization procedure, it is argument that may be sensitive to some drugs [53–55]. When ethanolic extract of A. tuncelianum was added to the culture medium, it was not changing the culture medium pH. In addition, another study showed that the ethanolic extract of garlic is more effective than the extract obtained from water [56].
In vitro drug discovery models for Mycobacterium tuberculosis relevant for host infection
Published in Expert Opinion on Drug Discovery, 2020
Drug discovery programs require robust and reliable primary and secondary screening assays, both to identify hits and to drive the discovery process. Key elements of a successful assay include reproducibility, capacity, ease of use, rapid assay turnaround, and relevance to the disease. This combination is difficult to achieve for tuberculosis, given a combination of the slow growth rate of the organism, the requirement to work in a controlled environment, and the complexity of the disease pathology. The simplest in vitro assays tend to have the least relevance for the infection setting. For example, they focus heavily on generating rapidly growing organisms in axenic culture. The development of truly reflective models would require heterogenous bacterial populations in different physiological states, but by their nature, these are the hardest in which to develop reliable data. A compromise between the two extremes has led to the development of increasingly sophisticated in vitro models, in which different aspects of infection can be modeled or mimicked.