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Treatment and drug development against free-living pathogenic amoebae
Jankovcová, Klára-Marie ; Mach, Jan (advisor) ; Vinopalová, Martina (referee)
Free-living pathogenic amoebae are cosmopolitan unicellular eukaryotic organisms, which can cause several serious infections in humans and animals. They are causative agents of amoebic encephalitis, which are very rare and acute diseases of the central nervous system, that almost always lead to the death of the patient. Even though the importance of these pathogens has been increasing in recent years, the development of treatment procedures and drugs against them is very ineffective and unsatisfactory. Treatment and drug development is complicated mainly because of the complex biological structure of pathogens and limited knowledge of metabolic pathways and the biochemical reactions that are occurring in them, which are crucial for the development of effective drugs. In this bachelor thesis I focus on the pathogenic species Naegleria fowleri, Balamuthia mandrillaris and the pathogenic genus Acanthamoeba, which is the causative agent of encephalitis and acanthamoeba keratitis. In the first part of this bachelor thesis, I generally characterize the different representatives of free- living pathogenic amoebae and describe the clinical picture of individual diseases. In the second part I address the issue of treatment. Firstly, I describe current therapeutic options and issues of the treatment of...
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Treatment options for untreatable amoeba Naegleria fowleri
Veselý, Martin ; Mach, Jan (advisor) ; Arbon, Dominik (referee)
Naegleria fowleri is a free-living protist which can penetrate the body of a previously healthy person and cause meningoencephalitis. The rapid course, disproportionately strong immune response and the lack of effective drugs are the reasons why this disease almost always ends fatally. Due to the relative rarity of this disease, it is not lucrative for pharmaceutical companies to develop a completely new drug. The only way to search for effective drugs is to test those that have already been approved for another purpose. However, clinical tests are not possible due to the low morbidity and rapid course of the disease, and research in this area is thus limited to animal models of the disease and evaluation of the effect of drugs against the pathogen in vitro. Currently used medication includes drugs that are highly toxic or poorly penetrate the site of inflammation. In the future, more effective chemotherapy against N. fowleri and more gentle towards patient could be used. This work summarizes knowledge about pathogenic amoeba, currently used drugs and presents new experimentally tested therapeutics.
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Free living amoebae as causative agents of human infections.
Markovičová, Ivana ; Nohýnková, Eva (advisor) ; Doležal, Pavel (referee)
Free living amoebae as causative agents of human infections are world wide occuring organisms with the ability of dual lifestyle both in nature, which is their original habitat, so within host tissue. The aim of this theses is to summarize the basic available knowledge of the pathogenic species Naegleria fowleri and Balamuthia mandrillaris and of the pathogenic genus Acanthamoeba which invade CNS and are causative agents of rare but serious human infections, often leading to death of a patient. The exception of their deathly consequences is an Acanthamoeba keratitis infection in which non curing cases lead to a significant visual impairment and even to visual loss. In each of the chapters, the work is tend to summarize transmision ability, mechanisms of pathogenesis and pathophysiology of these three free living amoebae in order to describe their ability to cause infection.
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Diagnostic and therapeutic approaches to infections caused by free-living amoebae pathogenic to humans
Štofaniková, Petra ; Nohýnková, Eva (advisor) ; Stejskal, František (referee)
Naegleria fowleri, Balamuthia mandrillaris and Acanthamoeba spp. are free-living amoebae which rarely cause human infections. N. fowleri induces primary amoebic meningoencephalitis mostly among children and young adults. B. mandrillaris is the causative agent of Balamuthia amoebic encephalitis and skin lesions with complicated healing. Amoebas of the genus Acanthamoeba are the ethiologic agent of focal granulomatous encephalitis. Its clinical presentation is almost the same as in Balamuthia encephalitis, but it occures mainly in immunocompromised patients. It can also affect lungs and skin. The infection of central nervous system usually has a fatal end. In immunocompetent people Acanthamoeba keratitis can occur. Unproper use of contact lenses or trauma of the cornea represents increased risk level. Without correct treatment Acanthamoeba keratitis can lead to sight loss. In all infections caused by free-living amoebae, early diagnosis and initialisation of effective therapy are essential for better prognosis. This thesis discusses contemporary diagnostic and therapeutic approaches to these infections.
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Molecular characterization of selected strains of amoebae of the genus Naegleria, the potential human parasites.
ZÍTKOVÁ, Klára
The genus Naegleria is a eukaryotic organism, one of those we can call "amoeba" a general name of creatures changing their shape during their locomotion. Amoebae comprise a huge number of various different genera some of which contain species able to infect humans similar to Naegleria fowleri. Two important exaples are the genera Acanthamoeba and Entamoeba, causative agents of acanthamoeba keratitis or diarrhoea, respectively, and other serious symptoms. Although superficially similar, they are not close relatives of Naegleria: they belong to Amoebozoa, whereas Naegleria is a Heterolobosea. The most important species of this speciose genus is the amoeba Naegleria fowleri. Is is the only Naegleria which is a human pathogen. After infection, it causes primary amoebic meningoecephalitis. The invasive stage of Naegleria is an amoebic trophozoite. Under certain circumstances, it can transform in another form, the flagellate bearing undullipodia. When the conditions worsen, it changes in the resistant cyst stage. Major part of my work is related to Naegleria fowleri and primary amebic meningoencephalitis, which causes human (PAM). They clarify here the source of infection and risk factors for assault. The length of incubation period and the first appearance of symptoms. The next chapter concerns the mechanism of intrusion into the body, how can this infection properly diagnose and detect and also a treatment option, resulting in early detection of symptoms. Possibilities prevention and epidemiology, including presentation of biggest epidemic, that happened in the Czech Republic. In the practical part of this thesis summarize my own study and methods used, as well as the results and their interpretation. The aim of the experimental part was the analysis of Naegleria DNA maintained in the collection of the laboratory of fish pathogens. To reach my goal and test the hypotheses of this thesis, I identified the Naegleria isolates. The final phylogenetic analysis was enriched with samples sequenced earlier, but so far not analyzed in any previous work. The first step in the workflow was the DNA isolation. The next one was to PCR amplify and sequence the ITS sequences to confirm they belong to Naegeria species, and to analyze the sequences phylogeneticaly and identify the species. The obtained sequences were edited in BioEdit software, program ClustalX was used to align them. The phylogenetic trees were computed in PAUP. Sequencing was provided by Seqme company. During the interpretation of the phylogenetic trees, I found which species were present in studied samples. They were as follows: two samples were N. americana, twelve others N. canariensis, three were N. dobsoni and there were also N. pagei and N. tihangensis one sample each. Several samples (GERK, MSED4, ALM1A, 62K4 and GG1BV) were different from any known species and it is therefore possible to consider them new, undescribed species. On the basis of this fact we can confirm the hypothesis nr. two: the species diversity is understudied and the recognition of new species probable. The data seem to support hypothesis 3: in a given locality, a single dominant species becomes dominant. In some localities, however, we could not fully exclude the opposing hypothesis 4.
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