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Molecular mechanisms of bacterial persistence to antibiotics
Jirsová, Anežka ; Lichá, Irena (advisor) ; Branny, Pavel (referee)
The ability to persist is inherent in the vast majority of bacterial species. Persisters represent a small heterogenous fraction of the bacterial population that can tolerate antibiotics. Unlike resistant cells, which are genetically distinct from the rest of the antibiotic-sensitive population, persister cells form a genetically indistinguishable subpopulation. Persisters arise either as a result of stress caused by adverse environmental conditions, or persister subpopulation arise as a result of stochastic induction independent of the presence of stressful conditions. There are various mechanisms by which bacterial cells have been shown to induce a persistent state. Toxin-antitoxin systems and their interaction with stringent response effectors play an important role during the development of persistence. The persistent state is also affected by changes in proton-motive force (PMF) and the fluctuations in the gene expression level of energy generating enzymes of the Krebs cycle (TCA). In this thesis, persister cells are characterized and the current knowledge about the molecular mechanisms leading to the induction of persistence in bacteria is summarized. Key words: bacteria, persistence, antibiotics, stringent response, PMF, TCA
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Ontogeny of dorsoabdominal scent gland complex in the representatives of the Pentatomoidea (Heteroptera).
Kutalová, Kateřina
Dorso-abdominal scent glands (= DAGs) of larvae represent one of apomorphic characters of insects order Heteroptera. These glands can persist until adults in different taxa. The persistence of DAGs were proved in the members of the family Acanthosomatidae. The ontogenetic development of DAGs cuticular structures were studied in all stadia, from 1st larval instar to adults of acanthosomatid Elasmucha ferrugata (Fabricius, 1787). The study concerned external structures and sculptures associated with DAG ostiole and areas of their surfaces, as well as internal structures, shape of gland reservoir and number of conducting ductules of proper glandular units. The light microscope and stereomicroscope and scanning electron microscope were used for this comprehensive study.
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Evaluation of TD test for analysis of persistence or tolerance in clinical isolates of Staphylococcus aureus
Kotková, Hana ; Lichá, Irena (advisor) ; Fišer, Radovan (referee)
Persistence is the ability of bacteria to survive the impact of antibiotics even when the bacteria do not encode resistance genes. This is a very complex process, which is probably consequence of a reduction physiological process in subpopulation of bacteria. The aim of this study was to verify the suitability of the newly developed "Tolerance Disk Test" (TD test, Gefen et al, 2017) for detection of persistent or tolerant subpopulations of bacterial cells in clinical isolates of Staphylococcus aureus. We performed TD test for this kind of bacteria, which is a significant opportunistic pathogenic organism in humans, and compared its results with the killing curves. We have found that the ability to persist can be monitored semi-quantitatively also in this case and we consider this test suitable for introduction into clinical practice. In addition, we suggest that TD test could distinguish between persistent and tolerant subpopulations. Key words: Staphylococcus aureus, persistence, antibiotics, tolerance
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Methods for characterization of persistent state after exposure to selected antibiotics in Staphylococcus aureus
Valtová, Aneta ; Lichá, Irena (advisor) ; Tkadlec, Jan (referee)
Staphylococcus aureus is a opportunistic pathogen that can cause severe and chronic infections. The reason of the infections relapse is often the persistence. It is about adapting to stressful conditions by inducing a dormant state, which would allow bacteria to survive exposure to antibiotics and grow again after their elimination. Bacteria that persist in the patient acquire various adaptive mutations, which are transmited creating subpopulations that have a better ability to persist. The aim of this diploma thesis was to compare individual methods of persistent study that could be used in clinical practice in the future, and at the same time to try a closer molecular characterization of the persistent state with using methods for calculating gene expression. I had chronological isolates of Staphylococcus aureus at my disposal, the initial one being the primoisolate, an isolate taken at the diagnostics of cystic fibrosis before the start of antibiotic treatment. Another was taken at a distance of three-quarters of a year and the last with a half-year interval from the previous one. Following whole genome sequencing, genes in which adaptive mutations occurred were identified. The first method determines the degree of persistence by calculating CFU (Colony Forming Units) after antibiotic treatment....
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Mechanisms of bacterial persistence and clinical significance
Smělíková, Eva ; Melter, Oto (advisor) ; Pinkas, Dominik (referee)
Persistent bacteria, shortly persisters, are cells that are characterized by their tolerance to antibiotics without containing resistance genes. These are not resistant bacteria, because resistant bacteria are determined by genetic code. Persisters are indistinguishable from other antibiotic sensitive bacteria, and they are rather transient phenotypic subpopulations. Probably all types of bacteria can create a persistent stage, the ability is not species-bound and persistence has been described in a number of bacterial species. The reason for the formation of persistence may be sudden stress, then it is induced formation, or the reason may be an insurance for the future, then we call it stochastic phenotypic variability. Then a variety of phenotypes of different subpopulations within a genetically uniform population can be distinguished. They differ in growth properties and tolerance to antibiotics. Bet-hedging strategy is a hypothesis that describes persistence as insurance against the risk of external fluctuations. During stress an alarmon guanosine tetraphosphate or guanosine pentaphosphate is accumulated to alert the cell to unfavorable conditions and it initiates transition to a more tolerant state. The existence of these tolerant subpopulations is important in recurrent diseases because small...
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Ontogeny of dorsoabdominal scent gland complex in the representatives of the Pentatomoidea (Heteroptera).
Kutalová, Kateřina
Dorso-abdominal scent glands (= DAGs) of larvae represent one of apomorphic characters of insects order Heteroptera. These glands can persist until adults in different taxa. The persistence of DAGs were proved in the members of the family Acanthosomatidae. The ontogenetic development of DAGs cuticular structures were studied in all stadia, from 1st larval instar to adults of acanthosomatid Elasmucha ferrugata (Fabricius, 1787). The study concerned external structures and sculptures associated with DAG ostiole and areas of their surfaces, as well as internal structures, shape of gland reservoir and number of conducting ductules of proper glandular units. The light microscope and stereomicroscope and scanning electron microscope were used for this comprehensive study.
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Patients' attitudes to pharmacotherapy of osteoporosis
Theimerová, Hana ; Vytřísalová, Magda (advisor) ; Hendrychová, Tereza (referee)
1 ABSTRACT PATIENTS' ATTITUDES TO PHARMACOTHERAPY OF OSTEOPOROSIS Author: Hana Theimerová Supervisor: Magda Vytřísalová Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Social and Clinical Pharmacy INTRODUCTION: Patients' attitudes to treatment might be affected by various factors. These may vary in different generations as well as in different populations. The patients' attitudes to the treatment along with the illness may affect decision concerning the beginning, interruption or end of the treatment. That implies that the interaction between these factors and attitudes to the treatment is comprehensive. AIMS: The study aim was to evaluate the patients' attitudes to the treatment of osteoporosis based on the perception of necessity and concerns of treatment with oral bisphosphonates (BIS). METHODS: Data for the analysis were obtained using an anonymous questionnaire in five outpatient centres in the Czech Republic from November 2012 to March 2013. The patients' opinions concerning the BIS treatment were identified (necessity vs. concerns) using the Czech version of the "Beliefs about Medicines Questionnaire Specific" (BMQ-CZ). RESULTS: A total of 363 patients were involved in the analysis (mean age 68.9 years). Patients were treated with once a week dosing forms of BIS -...
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Adherence to pharmacotherapy of osteoporosis
Santariová, Martina ; Vytřísalová, Magda (advisor) ; Doseděl, Martin (referee)
ADHERENCE TO PHARMACOTHERAPY OF OSTEOPOROSIS Author: Martina Santariová Supervisor: PharmDr. Magda Vytřísalová, Ph.D. Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Social and Clinical Pharmacy INTRODUCTION: Adherence is the extent to which the patient's behavior (using of medication, following recommended regimen) is in accordance with the advice of the health care provider. Adherence to pharmacotherapy of osteoporosis, including compliance and persistence, is still suboptimal. OBJECTIVE: The objective of the study was assessing of subjectively evaluated adherence with peroral bisphosphonates used to treat osteoporosis within Czech women. METHODS: A cross-sectional multicentre survey. Data collecting was carried out using anonymous questionnaire in five osteocenters in the Czech Republic. The research was performed between November 2012 and March 2013. Adherence was evaluated using a standardized questionnaire OS- MMAS (Osteoporosis-specific Morisky Medication Adherence Scale). RESULTS: A total of 363 postmenopausal women aged 55 years and older with osteoporosis or osteopenia were participated in the study. 133 (36,6 %) women used weekly dosage forms of BIS (alendronate, alendronate and vitamine D in a fixed combination, risedronate) and 230 (63,4 %) women used...
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The phenomenon of persistence in bacteria - the role of toxin-antitoxin systems.
Váchal, Martin ; Lichá, Irena (advisor) ; Seydlová, Gabriela (referee)
Most bacterial species currently studied are able to generate a small fraction of heterogeneous persister cells which are tolerant to antibiotics or other antimicrobials and still genetically identical to the susceptible parental population. Bacterial persisters emerge as a result of the stochastic regulation of cellular processes. Persistence can be triggered by stressful environmental stimuli or emerge spontaneously under favourable growth conditions. According to their origin, persistent subpopulations were divided into type I and type II persisters. Many recent studies indicate that toxin-antitoxin (TA) systems increase persistence. TA systems are ubiquitous genetic elements in prokaryotes and consist of a stable toxin, inhibiting essential cellular functions in persister cells, and an unstable antitoxin, which counteracts the activity of its toxin. Overexpression of toxin parts in excess of their corresponding antitoxin leads to multidrug tolerance (MDT). This work summarizes causes of persister formation and their hypothetical survival strategies and deals primarily with TA systems, controlling bacterial persistence of model organism Escherichia coli. The emphasis is put on the description of type I TA system TisB/IstR-1, type II TA systems HipBA, RelBE, MazEF, DinJ-YafQ, MqsRA, type V TA...
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