Search results for "Pathogen"

Blastocystis sp., an emerging parasite with controversial pathogenicity. Should all human cases be treated?

2018

Anti-Listeria activity of lactic acid bacteria in two traditional Sicilian cheeses

2017

<em>Listeria monocytogenes</em> is a pathogen frequently found in dairy products, and its growth is difficult to control. Bacteriocinlike inhibitory substances (BLIS), produced by lactic acid bacteria (LAB), having proven <em>in vitro</em> anti-<em>Listeria</em> activity, could provide an innovative approach to control <em>L. monocytogenes</em>; however, this application needs to be evaluated <em>in vivo</em>. In this study, twenty LAB strains isolated from different Sicilian dairy environments were tested for control of growth of <em>L. monocytogenes</em> in three different experimental trials. First, raw and UHT milk …

Different food sources elicit fast changes to bacterial virulence

2016

Environmentally transmitted, opportunistic bacterial pathogens have a life cycle that alternates between hosts and environmental reservoirs. Resources are often scarce and fluctuating in the outside-host environment, whereas overcoming the host immune system could allow pathogens to establish a new, resource abundant and stable niche within the host. We tested if short-term exposure to different outside-host resource types and concentrations affect Serratia marcescens —(bacterium)'s virulence in Galleria mellonella (moth). As expected, virulence was mostly dictated by the bacterial dose, but we also found a clear increase in virulence when the bacterium had inhabited a low (versus high) re…

Chromosome-Encoded Hemolysin, Phospholipase, and Collagenase in Plasmidless Isolates of Photobacterium damselae subsp. damselae Contribute to Virulen…

2017

ABSTRACT Photobacterium damselae subsp. damselae is a pathogen of marine animals, including fish of importance in aquaculture. The virulence plasmid pPHDD1, characteristic of highly hemolytic isolates, encodes the hemolysins damselysin (Dly) and phobalysin (PhlyP). Strains lacking pPHDD1 constitute the vast majority of the isolates from fish outbreaks, but genetic studies to identify virulence factors in plasmidless strains are scarce. Here, we show that the chromosome I-encoded hemolysin PhlyC plays roles in virulence and cell toxicity in pPHDD1-negative isolates of this pathogen. By combining the analyses of whole genomes and of gene deletion mutants, we identified two hitherto uncharacte…

Lepidopteran species have a variety of defence strategies against bacterial infections

2017

The insect immune system has versatile ways of coping with microbial insults. Currently, innate immune priming has been described in several invertebrates, and the first insights into its mechanistic basis have been described. Here we studied infections with two different strains of Serratia marcescens bacteria in two different Lepidopteran hosts. The results reveal fundamental differences between the two hosts, a well-known model organism Galleria mellonella and a non-model species Arctia plantaginis. They differ in their strategies for resisting oral infections; priming their defences against a recurring sepsis; and upregulating immunity related genes as a response to the specific pathoge…

Effect of resource availability on evolution of virulence and competition in an environmentally transmitted pathogen

2018

Understanding ecological and epidemiological factors driving pathogen evolution in contemporary time scales is a major challenge in modern health management. Pathogens that replicate outside the hosts are subject to selection imposed by ambient environmental conditions. Increased nutrient levels could increase pathogen virulence by pre-adapting for efficient use of resources upon contact to a nutrient rich host or by favouring transmission of fast-growing virulent strains. We measured changes in virulence and competition in Flavobacterium columnare, a bacterial pathogen of freshwater fish, under high and low nutrient levels. To test competition between strains in genotype mixtures, we devel…

COVID-19 severity associates with pulmonary redistribution of CD1c+ DCs and inflammatory transitional and nonclassical monocytes

2020

SARS-CoV-2 is responsible for the development of coronavirus disease 2019 (COVID-19) in infected individuals, who can either exhibit mild symptoms or progress toward a life-threatening acute respiratory distress syndrome (ARDS). Exacerbated inflammation and dysregulated immune responses involving T and myeloid cells occur in COVID-19 patients with severe clinical progression. However, the differential contribution of specific subsets of dendritic cells and monocytes to ARDS is still poorly understood. In addition, the role of CD8+ T cells present in the lung of COVID-19 patients and relevant for viral control has not been characterized. Here, we have studied the frequencies and activation p…

Genome-Wide Estimation of the Spontaneous Mutation Rate of Human Adenovirus 5 by High-Fidelity Deep Sequencing

2016

Rates of spontaneous mutation determine the ability of viruses to evolve, infect new hosts, evade immunity and undergo drug resistance. Contrarily to RNA viruses, few mutation rate estimates have been obtained for DNA viruses, because their high replication fidelity implies that new mutations typically fall below the detection limits of Sanger and standard next-generation sequencing. Here, we have used a recently developed high-fidelity deep sequencing technique (Duplex Sequencing) to score spontaneous mutations in human adenovirus 5 under conditions of minimal selection. Based on >200 single-base spontaneous mutations detected throughout the entire viral genome, we infer an average mutatio…

2020

Atopic dermatitis (AD) is characterized by chronic, relapsing, pruritic skin inflammation and does not have a well-understood pathogenesis. In this study, we addressed the contribution of adipokines to AD eczema based on the assessment of blood levels of adiponectin, resistin, leptin, lipocalin-2, and vaspin in adult non-obese patients suffering from chronic extrinsic childhood-onset AD. We investigated 49 AD patients with a median age of 37 years. The control group consisted of 30 age-matched healthy subjects. Adipokines were assessed in the serum by ELISA assays and the severity of AD with the SCORing Atopic Dermatitis (SCORAD) index. We found that adiponectin and resistin decreased and l…

Early effects of fluoro-edenite: correlation between IL-18 serum levels and pleural and parenchymal abnormalities.

2016

Fluoro-edenite (FE) is a natural mineral asbestos-like fibrous species first isolated in Biancavilla, Sicily. In order to clarify potential involvement of IL-18 in the pathogenesis of FE-induced chest abnormalities, we analyzed IL-18 serum levels in FE-exposed workers (FEEW) and correlated them with pleural and parenchymal abnormalities. A total of 21 FEEWs, residing in Biancavilla for >30 years, with a working seniority of 17 ± 6.1 years were examined. High-resolution computed tomography scans revealed low grade of fibrosis in 8 (38%) FEEWs, and pleural plaques (PPs) in 13 (62%) FEEWs. The mean IL-18 level was 203.13 ± 90.43 pg/ml. Pearson correlation showed a significant association (…