All posts by Postępy Mikrobiologii

Polio – zagadkowy wirus

Polio – a mysterious virus
Ł. Kuryk, M. Wieczorek, B. Litwińska
16 October 2017

1. Wstęp. 2. Rys historyczny. 3. Budowa. 3.1. Genom. 3.2. Kapsyd. 4. Namnażanie wirusa polio. 4.1. Wniknięcie do komórki. 4.2. Synteza białek wirusowych. 4.3. Replikacja RNA. 5. Przebieg zakażenia wirusem polio. 6. Neurowirulencja. 7. Tropizm tkankowy wirusa polio. 8. Szczepionki przeciwko wirusowi polio. 9. Program eradykacji poliomyelitis. 10. Podsumowanie

Abstract: Poliovirus is a very small virus; single stranded RNA of positive polarity constitutes its genetic material. It belongs to the Picornaviridae family and may cause the development of poliomyelitis (viral inflammation of the anterior horn of the spinal cord). At the beginning of the twentieth century, the epidemics of polio were very frequent and this fact caused an increased interest in this virus. At present, there are two types of polio virus vaccines: OPV (oral polio vaccine), which contains three serotypes of live attenuated virus and inactivated vaccine IPV (inactivated polio vaccine) containing inactive virus particles. In 1988, the World Health Organization (WHO) introduced the program of global eradication of wild-type polio virus around the world (Global Polio Eradication Initiative). The outbreaks of wild-type polio still occur in Asia and Africa. Possibility of reversion of vaccine strains of polio virus to wild type carries the fear of re-transmission of the pathogen. It is the most intensively studied enterovirus, but still remains a puzzle.

1. Introduction. 2. Historical background. 3. Structure. 3.1. Genome. 3.2. Capsid. 4. Cellular life cycle of poliovirus. 4.1. Cell entry. 4.2. Synthesis of viral proteins. 4.3. RNA Replication. 5. Poliovirus pathogenesis. 6. Neurovirulence. 7. Poliovirus tissue tropism. 8. Vaccines against poliovirus. 9. The polio eradication initiative. 10. Summary

Autor: Postępy Mikrobiologii
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Wirusy paragrypy w aspekcie zakażeń wirusowych osób po przeszczepach szpiku lub płuc

Human parainfluenza viruses as the cause of viral infectionsin patients after stem cells or lung transplantation
E. Abramczuk, K. Pancer, B. Litwińska
16 October 2017

1. Wstęp. 2. Ogólna charakterystyka hPIV oraz zakażeń przez nie wywołanych. 3. Zakażenia hPIV u pacjentów po przeszczepach narządów. 4. Diagnostyka i leczenie. 5. Podsumowanie

Abstract: The characteristics of human parainfluenza viruses (hPIVs) are presented. These viruses are well known as the agents of respiratory tract infections (RTI) in children. The incidence of hPIV infections varieds depending on the year/season. The reinfections occurre throughout the life. In immunocompromised patients such reinfections might be a cause of severe disease (pneumonia, GVPD) beading also to death. Nowadays, transplantation has become a successful worldwide practice. According to WHO, more than 50.000 stem cells transplantations are carried out annually, the lung transplantation – 3500/year. In lung recipients, hPIV is the first agent of RTI; in stem cells recipients – the second (after RSV). The hPIVs infections have been observed in 1,5–10% of lung recipients and in 2,2–60% of stem cells recipients and the predominant virus was hPIV-3. The patients after transplantation receive high doses of corticosteroids which increase the risk of hPIV-pneumonia, a life threating disease, and quick diagnosis is required. Moreover, hPIVs are also the cause of nosocomial infections. Such outbreak/cases occur simultaneously to the activity of the viruses in the environment. In immunocompromised patients the shedding of hPIVs is significantly longer than in immunocompetent persons, also the infection can be asymptomatic for the weeks. Such patients, visitors of their families, especially children, and staff members are the source of nosocomial hPIVs infections. Considering the lack of specific and effective anti-hPIVs therapy it is very important to prevent them. The most effective way of prevention is the compliance with the fundamental hygienic behaviours and the restriction of contact with ill people.

1. Introduction. 2. General characteristic of hPIVs and infection caused by them. 3. hPIV infection in patients after organ transplants. 4. Diagnosis and treatment. 5. Summary

Autor: Postępy Mikrobiologii
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Probiotyki – aspekty funkcjonalne i technologiczne

Probiotics – technological and manufacturing aspects
M. Jach, R. Łoś, M. Maj, A. Malm
16 October 2017

1. Wstęp. 2. Otrzymywanie, selekcja i właściwości szczepów probiotycznych. 3. Bezpieczeństwo probiotyków. 4. Otrzymywanie produktów probiotycznych. 5. Probiotyki przyszłości – farmabiotyki? 6. Podsumowanie

Abstract: Probiotics are bacteria of natural human microbiota which have positive effect on the host organism physiology. Probiotic strains which are selected from wild strains have to possess certain qualities such as: being competitive against pathogens, synthesizing appropriate metabolic products and ability to adhere. Probiotic strains also have to show properties which allow them to be safe to use as well as render them resistant to conditions occurring during production processes and in human gastrointestinal tract. Inversely – the production processes used in the preparation of probiotics, have to be adjusted to maintain acceptable survival rates of bacteria. Pharmabiotics are a particular kind of probiotics, modified using genetic engineering to achieve desirable traits, either functional or technological.

1. Introduction. 2. Preparation, selection and properties of probiotic strains. 3. Safety of probiotics. 4. Production of probiotic products. 5. Pharmabiotics – probiotics of the future? 6. Summary

Autor: Postępy Mikrobiologii
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Oporność Staphylococcus aureus na glikopeptydy

Resistance of Staphylococcus aureus strains to glycopeptides
K. Szymanek -Majchrzak, A. Młynarczyk, G. Młynarczyk
16 October 2017

1. Wstęp. 2. Wankomycyna i inne glikopeptydy. 2.1. Charakterystyka antybiotyków. 2.2. Kryteria wrażliwości na glikopeptydy. 3. Nabyta oporność na wankomycynę. 3.1. Enterokoki VRE. 3.2. Transfer operonu vanA ze szczepów Enterococcus spp. do izolatów metycylino-opornych Staphylococcus aureus – możliwości i obawy. 3.3. Wankomycyno-oporne szczepy Staphylococcus aureus (VRSA). 3.3.1. Mechanizm oporności u VRSA warunkowany obecnością operonu vanA. 3.3.1.1. Heterologiczna ekspresja operonu vanA u wankomycyno-opornych S. aureus. 3.3.1.2. Wankomycyno-oporne S. aureus – analiza przypadków. 3.3.1.3. Epidemiologia szczepów VRSA vanA. 3.3.2. Szczepy VRSA – vanA-negatywne (dawne Staphylococcus aureus o obniżonej wrażliwości na wankomycynę, VISA) – pochodzenie oraz mechanizm oporności. 4. Szczepy Staphylococcus aureus wykazujące fenotyp hetero-VISA. 5. Opcje terapeutyczne leczenia ciężkich zakażeń o etiologii S. aureus, wobec których terapia wankomycyną pozostaje nieskuteczna. 6. Podsumowanie

Abstract: Until recently, vancomycin was perceived as an effective drug for the treatment of serious infections with MRSA etiology. For over 30 years, since the introduction of the antibiotics on the pharmaceutical market, there was no case of Staphylococcus aureus resistant to the glycopeptide and it seemed that strains of S. aureus are naturally sensitive to vancomycin. Problems began to appear at the beginning of the 90s of the twentieth century, when more and more treatment failures with the use of the glycopeptide antibiotics were being reported. Strains of S. aureus which may manifest decreased susceptibility or resistance to vancomycin and/or teicoplanin were recognized as the main cause of these failures. VRSA (vancomycin resistant S. aureus), with the genotype vanA conditioned by the presence of vanA operon transmitted from Enterococcus are extremely rare. More frequent are VISA (vancomycin intermediate S. aureus) or VRSA vanA-negative strains exhibiting thickened cell walls, increased content of free dipeptide D-Ala-D-Ala in peptidoglycans and disorders in autolytic processes, and hetero-VISA strains sensitive to vancomycin (MICVA ≤2 mg/L), but containing subpopulations of cells exhibiting MIC values at different levels. These effects are caused by different molecular mechanisms, which are related to different regulatory systems and manifested by diverse phenotypic features, but the result is always the lack of treatment efficacy. A review of the mechanisms leading to the formation and spread of S. aureus isolates for which the vancomycin treatment can be ineffective has become an essential objective of this monograph.

1. Introduction. 2. Vancomycin and other glycopeptides. 2.1. Characteristics of the antibiotics. 2.2. Criteria of sensitivity to glycopeptides. 3. Transferred resistance to vancomycin. 3.1. Enterococci VRE strains. 3.2. The vanA operon transfer from Enterococcus spp. to methicillinresistant Staphylococcus aureus strains – possibilities and apprehensions. 3.3. Vancomycin-resistant Staphylococcus aureus strains (VRSA). 3.3.1. Mechanism of resistance of VRSA strains – determination the presence of vanA genes. 3.3.1.1. Heterologic expression of vanA operon in vancomycin-resistant S. aureus. 3.3.1.2. Vancomycin-resistance of S. aureus – case studies. 3.3.1.3. Epidemiology of VRSA vanA strains. 3.3.2. VRSA strains – vanA-negative (previous vancomycin intermediate Staphylococcus aureus, VISA) – provenance and mechanism of resistance. 4. The hetero-VISA phenotype expression in Staphylococcus aureus strains. 5. Therapeutic options for the treatment of serious infections with S. aureus etiology for which vancomycin therapy remains ineffective. 6. Summary

Autor: Postępy Mikrobiologii
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Metagenom – zródło nowej informacji o mikroorganizmach glebowych

Metagenome – a new source of information about soil microorganisms
J. Kozdrój
16 October 2017

1. Wstęp. 2. Problemy z poznaniem mikrobiomu oraz próby ich przezwyciężania. 3. Metagenomika a specyficzny charakter gleby. 4. Analiza genetyczna mikrobiomu. 5. Analiza funkcjonalna metagenomu. 6. Strukturalna różnorodność mikroorganizmów w różnych środowiskach glebowych. 7. Podsumowanie

Abstract: Soil environment, due to its high heterogeneity, is considered as a major reservoir of microbial genetic and metabolic diversity in the biosphere. The knowledge on this diversity is limited, because most of the soil microorganisms cannot be cultured under the usual laboratory conditions. During the last two decades, development of methods to isolate nucleic acids from soil has opened a window to a previously unknown microbial world. In consequence, a new metagenomic approach based on the analyses of total microbial DNA has appeared in soil studies. Total microbial DNA extracted from soil by direct or indirect methods is mostly used for amplification of marker genes (e.g. SSU rRNA) which is further differentiated by fingerprinting (e.g. DGGE, T-RFLP) or sequenced directly. Until recently, sequencing was mainly performed after first cloning PCR products to produce a clone library of amplicons. Lately, another approach has been introduced to reduce costs and labour; it is commonly known as 454-pyrosequencing, the method that does not require cloning. These methods as well as DNA microarrays have demonstrated an unanticipated level of microbial diversity, especially in the newly discovered world of the biosphere. Thousands or even several hundred thousands of different bacterial phylotypes can be present in a gram of soil. They belong to dozens of phyla. The molecular approach changed the picture of structural diversity of soil microbiome, also indicating that bacteria, archaea, fungi and even viruses are diverse both globally and locally. Moreover, soil metagenomics, allows for a comprehensive search for gene expression and metabolic activity within microbiome.

1. Introduction. 2. Difficulties with microbiome analysis and attempts to overcome them. 3. Metagenomics vs. distict features of soil. 4. Genetic analysis of microbiome. 5. Functional analysis of microbiome. 6. Microbial structural diversity in different soil environments. 7. Summary

Autor: Postępy Mikrobiologii
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Advancements of Microbiology
Volume 63 (2024): Issue 3

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PTM

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