Browsing tag: czynniki wirulencji

Czynniki wirulencji grzybów z rodzaju Candida istotne w patogenezie zakażeń występujących u pacjentów żywionych pozajelitowo

Virulence factors of Candida species important in the pathogenesis of infections in patients with total parenteral nutrition
M. Sikora, M. Gołaś, K. Piskorska, E. Swoboda-Kopeć

1. Wstęp. 2. Czynniki ryzyka wystąpienia zakażenia o etiologii grzybiczej. 3. Czynniki wirulencji grzybów drożdżopodobnych z rodzaju Candida. 4. Zjawisko wzrostu w postaci biofilmu. 5. Sekrecja enzymów hydrolitycznych. 6. Zjawisko dimorfizmu. 7. Podsumowanie

Abstract: Fungal infections constitute a vital clinical issue concerning various groups of patients, among them patients with total parenteral nutrition. The most common etiological infection factors, affecting the aforementioned group of patients, are among others yeastlike fungi. In clinical specimens, the predominant genus of yeastlike fungi, as isolated from the patients with total parenteral nutrition, is Candida spp. The species of yeastlike fungi of the Candida genus generate various pathogenic factors enabling invasion process and the progression of the subsequent infection stages. The most crucial of them are:
• ability to adhere and ability to form biofilms. This feature, with the mediation of adhesion proteins, enables the fungi to grow on the biomaterial surfaces, to invade the host’s tissue, and conditions survival and existence in the environment;
• dimorphism. Creation of two antigenically different forms – yeast and hyphae – conditions specific escape from the immunological system of the macroorganism;
• high enzymatic activity. Hydrolytic, proteolytic and lipolytic activity, featuring primarily the adaptative function, is the indicator of the metabolic stimulation required for the infection process,
Due to the insignificant pathogenic potential of the Candida genus fungi, associated with the fact of their natural existence on skin and mucous membrane, the research is currently often directed at detection of the factors responsible for the colonisation and development of the fungal infections. These research attempts are aimed at differentiating between both processes.

1. Introduction. 2. Risk factors of fungal infections. 3. Virulence factors of the Candida genus. 4. The phenomenon of biofilm formation. 5. Hydrolytic enzymes secretion. 6. Dimorphism. 7. Conclusions

Streptococcus pneumoniae – kolonizacja a rozwój choroby pneumokokowej

Streptococcus pneumoniae – colonization and pneumococcal disease
I. Korona-Głowniak, A. Malm

1. Wstęp. 2. Kolonizacja nosogardłowa przez Streptococcus pneumoniae jako prekursor choroby. 3. Czynniki chorobotwórczości S. pneumoniae i ich znaczenie w patogenezie zakażeń. 4. Patogeneza zakażenia pneumokokowego. 5. Odporność przeciwpneumokokowa gospodarza. 6. Profilaktyka zakażeń pneumokokowych. 7. Podsumowanie

Abstract: Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, especially in young children and elderly people. Pneumococcus is the leading cause of non-invasive (pneumonia, sinusitis, otitis media) and invasive (meningitis and bacteriemia/sepsis) pneumococcal disease. The virulence of S. pneumoniae is dependent on numerous factors. Nasopharyngeal carriage of pneumococcus precedes disease and is the source of pneumococcal spread in the community. Although the relationship between carriage and disease is not well understood, a lot of data suggest that local or invasive infection is caused by serotypes which previously bind to the epithelial surface within the respiratory tract. Pneumococcal conjugate vaccines effectively prevent the most serious forms of pneumococcal disease caused by serotypes included in the vaccines and also reduce the risk of nasopharyngeal carriage by those serotypes. Recently, studies were carried out on the immunogenicity and significance of numerous protein virulence factors for the induction of serotype-independent protection against pneumococcal infection.

1. Introduction. 2. Nasopharyngeal colonization by Streptococcus pneumoniae as disease precursor. 3. Virulence factors of Streptococcus pneumoniae and their impact on the development of pneumococcal disease. 4. Pathogenesis of pneumococcal disease. 5. Antipneumococcal host immunity. 6. Pneumococcal vaccines. 7. Summary

Udział czynników wirulencji Enterococcus faecalis w rozwoju chorób miazgi i tkanek okołowierzchołkowych

Virulence factors of Enterococcus faecalis in relation to pulp diseases and periapical infections
E. Prażmo, R. Godlewska, M. Kwaśny, A. Mielczarek

1. Wstęp. 2. Znaczenie E. faecalis w zakażeniach endodontycznych zębów. 3. Czynniki wirulencji E. faecalis. 4. Mechanizmy zjadliwości E. faecalis. 5. Podsumowanie

Abstract: Enterococci are Gram-positive, catalase-negative, facultative anaerobic bacteria. They inhabit the oral cavity and gastrointestinal tract in humans as normal commensals. However, they can also cause infections of the urinary tract, surgical wound infections, neonatal sepsis and endocarditis. Enterococcus faecalis is associated with great number of refractory endodontic infections. The prevalence of these bacteria ranges from 24 to 77% in teeth with failed endodontic treatment and E. faecalis very often coexists with chronic apical periodontitis. Understanding the virulence, ecology and epidemiology of E. faecalis is essential for limiting all kinds of diseases caused by this pathogen. This article focuses on the bacterial mechanisms related to endodontic infections and periradicular inflammatory response. The most explored virulence factors are: the aggregation substance, surface adhesins, lytic enzymes, lipoteicholic acid, sex pheromones. All of them are associated with specific stages of tissue invasion. E. faecalis has also developed elaborated mechanisms of antibiotic resistance, as well as the ability to organize in a biofilm and overcome low-nutrient conditions. These adaptations help in the modulation of host immune response and make E. faecalis very difficult to eradicate by available antibiotics and disinfectants. Recognition and understanding of the nature of this pathogen will help endodontic microbiology to completely eliminate endodontic infections for successful endodontic treatment.

1. Introduction. 2. Importance of E. faecalis in endodontic infections. 3. Virulence factors of E. faecalis. 4. Virulence mechanisms of E. faecalis. 5. Summary