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Search Results: 1 - 10 of 712 matches for " Virulence "
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In Vitro Mitigation of Pathogenic Bacteria and Virulence Factors Using a Hydroconductive Dressing  [PDF]
Lauren T. Moffatt, Rachel T. Ortiz, Bonnie C. Carney, Rachael M. Bullock, Martin C. Robson, Marion H. Jordan, Jeffrey W. Shupp
Surgical Science (SS) , 2013, DOI: 10.4236/ss.2013.411094

Wound infections can have devastating effects on healing as well as the health of the patient. Complications increase when the pathogens are capable of producing virulence factors and/or are drug resistant. Novel methods are needed to take on the challenges of treating such wounds. Drawtex® dressing is purported to have hydroconductive properties that allow it to draw away debris and exudate from the wound into the dressing. The goal of this work is to better define these interactions of this experimental dressing with bacteria and virulence factors. Two series of in vitro experiments were performed. First, pieces of experimental dressing were submerged in a series of cultures in flasks and samples of the dressing and cultures were taken over 90 minutes and assayed for bacteria and virulence factor levels. Second, experimental or standard care (control) dressings were placed on selective agar plated with pathogens of interest. Dressings and the agar covered by them were used to quantify bacteria and virulence factors over time. The experimental dressing took up both bacteria and virulence factors to a larger extent than the control dressing. Experimental dressing significantly reduced the load of bacteria and virulence factors in cultures compared to control culture without dressing. Based on the ability of the dressing to take up bacteria and virulence factors in this study, the data point to the potential for this dressing to be similarly effective in reducing or

The omp2 Gene of HPS-type Bacteria Cloning and Sequence Analysis Isolates from Sichuan Province  [PDF]
Lirui Li, Zexiao Yang, Yin Wang, Qiu Jin, Xulong Wu, Rongchang Zhang
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.410B040

In order to compare the homology and antigen of Haemophilus parasuis (HPS)4 outer membrane protein P2(omp2), we design a test with specific primers, using PCR amplification of isolates of Haemophilus parasuis from Sichuan Province(HP Sch2010), ompP2 gene will be cloned into the pGM-T vector, and transformed into E. coli DH5α. Identified by PCR and sequencing and analysis, the sequencing results showed that the published 4 HPS SW124 strains omp2 gene (1077bp), compared with the amplified 1086bp purpose fragment(containing omp2 genes), is relatively stable, with the nucleotide homology level 97% and amino acid homology level of 92.5%. The variable regions are mainly concentrated in the three base sequences: 40-65,110-156,180-202.

Virulence Factors in Methicillin-Resistant Staphylococcus aureus Isolated from ICU Units in Brazil  [PDF]
Simone G. Souza, Guilherme B. Campos, Pollianna S. Oliveira, Daniel S. Sousa, Danilo C. C. Da Silva, Verena M. Santos, Aline T. Amorim, Angelita M. O. G. Santos, Jorge Timenetsky, Mariluze P. Cruz, Regiane Yatsuda, Lucas M. Marques
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.44027

Species of Staphylococcus are common in hospital infection (HI). Methicillin resistant S. aureus (MRSA) has also become a serious problem in Brazilian HI. The aim of this study was to characterize the pathogenicity of methicillin-resistant S. aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) isolated in public hospitals. The clinical isolates were obtained from intensive care unit. The MRSA and MSSA strains were genotyped by PCR for detection genes related to virulence factors. Moreover, the strains were tested for biofilm formation and cytokine induction in macrophages. Three strains of MRSA (9.68%) expressed the Sea gene, one (3.23%) Seb, 17 (54.84%) Spa and seven (22.58%) had PVL. Two MSSA strains (2.98%) expressed the Sea gene, three (4.48%) Seb, 18 (26.87%) Spa and 11 (16.42%) showed positive results for the PVL gene. There was no expression of Sec and CflA between MRSA and MSSA strains. Among MRSA and MSSA isolates, none statistical differences were observed in biofilm production. The analysis of cytokine induction in the inflammatory response of J774 macrophages by MRSA and MSSA isolates did not show statistical difference. Understanding the mechanisms of pathogenesis of S. aureus could provide important clues for both preventing and treating infection caused by these organisms.

Insights into Pneumococcal Pathogenesis and Antibiotic Resistance  [PDF]
Eric S. Donkor, Ebenezer V. Badoe
Advances in Microbiology (AiM) , 2014, DOI: 10.4236/aim.2014.410069

Since its discovery in 1891, the pneumococcus has been one of the most extensively studied microbes, and was involved in several historical findings such as the discovery of genetic material that was later shown to be DNA. The pneumococcus is part of the normal bacterial flora of the nasopharynx, but can on occasions progress to sterile sites of the body and cause invasive diseases. There are about one million new invasive pneumococcal infections every year, majority of which occur in the developing world where children <5 years are most affected. The burden of pneumococcal disease is further heightened by the increasing prevalence of multidrug resistance of the organism. The pneumococcus remains a pathogen of immense public health significance and understanding its biology, particularly the pathogenesis and antibiotic resistance is crucial to controlling pneumococcal disease.

AAA+ ClpB chaperone as a potential virulence factor of pathogenic microorganisms: Other aspect of its chaperone function  [PDF]
Joanna Krajewska, Sabina K?dzierska-Mieszkowska
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.51005

We describe and discuss the most recent findings on the activity and function of the oligomeric AAA+ chaperone ClpB from the Hsp100 protein family in pathogenic microorganisms. Pathogens are exposed to significant stress during infection of the host cells, frequently resulting in protein aggregation. The fact that ClpB is usually up-regulated in pathogens together with its immune reactivity suggests that ClpB acting as a protein disaggregase may be important for pathogen invasion and virulence. However, the specific function of ClpB in pathogenicity is still unclear. Since it is known that ClpB does not exist in mammals, it may serve as a potential target for the development of an effective therapy against several major bacterial diseases that do not respond to conventional antibiotics.

Occurrence of apocrine secretion in the larval gut epithelial cells of Aedes aegypti L., Anopheles albitarsis Lynch-Arribálzaga and Culex quinquefasciatus say (Diptera: Culicidae): a defense strategy against infection by Bacillus sphaericus Neide?
Oliveira, Caroline D;Tadei, Wanderli P;Abdalla, Fábio C;
Neotropical Entomology , 2009, DOI: 10.1590/S1519-566X2009000500010
Abstract: cell hypertrophy was the first reaction of the gut epithelial cells of aedes aegypti (l.), anopheles albitarsis (lynch-arribálzaga) and culex quinquefasciatus (say) to the toxins of strains 2362 and s1116 of bacillus sphaericus, as cells had an increase of intracellular secretory activity. soon after the cell hypertrophy developed, vesicles were formed at the cell apical portion, which detached with the plasma membrane, characterizing a type of apocrine secretion like. the first pathway of contamination of the mosquito larvae by these bacteria is through the gut, by feeding. depending on the species of culicidae and on the bacterial strain used, the hypertrophy of the gut epithelium occurred between 5 and 15 min after exposure to the contaminated environment. the second aspect observed after hypertrophy was the increase in apocrine secretion. the basophilic vesicles that detached from the cells remained between the peritrophic membrane and the gut lumen, such vesicles were filled with material of unknown nature. the gut posterior region showed secretory activity in both control and treated larvae, being much more intense in bacteria-exposed larvae. there were remarkable differences in the epithelial cell reaction according to the toxins of the two bacterial strains, but c.quinquefasciatus was the most susceptible. differences in the gut cell reactions to the toxins produced by the two bacterial strains are discussed.
Variability in isolates of Puccinia polysora in Brazil
Fitopatologia Brasileira , 2002, DOI: 10.1590/S0100-41582002000400015
Abstract: the main objective of this work was to evaluate the variability of the southern rust pathogen puccinia polysora in brazil, based on its virulence on a set of maize (zea mays) cultivars. sixty single pustule isolates, from different areas of occurrence of southern rust, were evaluated for their virulence to 50 maize experimental hybrids. six cultivars showed a clear distinction between susceptible and resistant reaction, and were used to characterize the variability of the pathogen. seventeen virulence patterns were identified among the 60 isolates tested. the most frequent virulence patterns identified, were observed in all locations of sampling, which suggests the absence of geographical differentiation among prevalent populations of p. polysora in brazil.
Factores asociados a la infección celular por el virus de la necrosis pancreática infecciosa (IPNV)
Ortega,C; Enríquez,R;
Archivos de medicina veterinaria , 2007, DOI: 10.4067/S0301-732X2007000100002
Abstract: the infectious pancreatic necrosis virus (ipnv) is one of the main causes of economic losses in salmon farms. its temporal expression and the characteristics of its components have been described in many studies, however, the role of proteins in viral pathogenesis has not been completely determined. the aim of this review is to detail the processes that allow the establishment of a virus-cell relationship, replication and dissemination of the infection, highlighting the role of the viral components in such mechanisms and the effect of their variability on viral virulence. the molecular mechanisms that characterize birnaviruses in relation to their replication, translation and maturity are also described. the host response and defense mechanisms against viral infection are mentioned, highlighting the importance of the non-specific immunity through stimulating the synthesis of antiviral proteins via interferon, and the importance of apoptosis as a defense mechanism that can be modulated by the virus? proteins. also, the role of viral and cell factors on the development of the carrier stage, which is considered one of the most important aspects in the dissemination of ipnv, is described.
Comparative virulence of Scedosporium species in animal models
Nweze, EI;Okafor, JI;
Brazilian Journal of Infectious Diseases , 2010, DOI: 10.1590/S1413-86702010000300012
Abstract: scedosporium species are an emerging opportunist group of fungi that have been found to cause infections in both immunocompetent and non-immunocompetent individuals. the infections are not regularly distributed among different countries of the world either because of improper identification or other geographical reasons. strange as it may, disseminated systemic infections have only been reported in some specific countries. we used a mouse model of disseminated infection to assess if strains from nigeria were virulent and compared it to a few other strains from other countries. s. apiospermum isolated from nigeria were clearly less virulent than those obtained elsewhere. this may be the reason why this group of fungi has not been associated with specific clinical problems in nigeria in pa'rticular and africa in general.
Búsqueda del plásmido de virulencia de Salmonella en aislamientos clínicos colombiano
CES Medicina , 2011,
Abstract: introduction: salmonella is a gram negative bacillus, intracellular pathogen that invades nonphagocytic intestinal cells and macrophages in a complex process that requires multiple genes. the salmonella virulence plasmid "spv" contains the spvr gene whose function is to increase its virulence producing systemic invasion in mice. methods: we search for spvr gene in human clinical isolates of salmonella spp from patients with systemic infection (typhoid fever) and with nonsystemic infection (diarrheal), in order to compare the presence of the gene to clinical outcome. spvr was searched in 55 clinical isolates of s. typhi from typhoid fever patients, 20 of s. enteritidis and 20 of s. typhimurium isolates from patients with diarrheal. pcr from chromosomal and plasmid dna was performed. the pcr products were sequenced and the sequences obtained from genomic and plasmid materials were compared using bioinformatics analysis. results: 55 (100 %) isolates of s. typhi were negative for spvr. 15 (75 %) isolates of s. enteritidis and 8 (40 %) of s. typhimurium were positive for spvr both from genomic and plasmid material. these results show that clinical isolates of s. typhi considered more virulent not showed spvr, and that diarrhea-producing serotypes s. enteritidis and s. typhimurium in 75 and 40 % respectively were positive for the gene, questioning the role of virulence of the gene in strains producing human infections. it also showed the presence of plasmid gene sequences homologous to chromosomal regions in the studied serotypes. conclusion: results show that the absence of the plasmid of salmonella's virulence is not related with the systemic outcome in the clinical isolates of salmonella typhi that were studied. there was also confirmed that exists chromosomal material homologous to the gene spvr virulence plasmid in the chromosome of serotypes s. enteritidis and s. typhimurium but similar material wasn't found in s. typhi chromosome.
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