38 research outputs found

    Study of <i>Salmonella</i> pathogenicity mechanisms in <i>vitro</i> and in <i>vivo</i>

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    Salmonella enterica subsp. enterica includes many pathogenic serovars. Models of the study are S. typhimurium and S. abortusovis, a restricted serovar to sheep. Bacterial pathogen’s transmission strategies are usually connected to pathogenesis and limited information is available about the immune response of sheep to S. abortusovis and about flagellin interaction with S. abortusovis. Knowledge about those factors are mainly based on studies of S. typhimurium. Here we try to understand the role of flagella in S. abortusovis. The idea is that S. abortusovis highly regulates expression of flagella within the host, and we performed studies to clarify how S. abortusovis evade activation of the immune system. Mutations in S. abortusovis flagella genes were generated and flagella from wild type and mutant’s strains of the two different serovars were extracted using diverse media to observe differences in flagellation and host interaction. Samples were analyzed by Western Blot to determine expression of major flagellar protein. Surface expression of flagella was verified by Flow Cytometry and by Scanning Electron Microscopy. To verify the capacity of S. typhimurium and S. abortusovis to stimulate TLR5, a colorectal carcinoma cell line (T84 cells) was treated with purified flagellin and the transcriptional induction of a CXC chemokine IL-8 was measured. We showed that S. abortusovis flagella are expressed in specific media, and they induced the transcription of IL-8 in T84 cells

    How microbiological tests reflect bacterial pathogenesis and host adaptation

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    Historically, clinical microbiological laboratories have often relied on isolation of pure cultures and phenotypic testing to identify microorganisms. These clinical tests are often based on specific biochemical reactions, growth characteristics, colony morphology, and other physiological aspects. The features used for identification in clinical laboratories are highly conserved and specific for a given group of microbes. We speculate that these features might be the result of evolutionary selection and thus may reflect aspects of the life cycle of the organism and pathogenesis. Indeed, several of the metabolic pathways targeted by diagnostic tests in some cases may represent mechanisms for host colonization or pathogenesis. Examples include, but are not restricted to, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella enterica, Shigella spp., and enteroinvasive Escherichia coli (EIEC). Here, we provide an overview of how some common tests reflect molecular mechanisms of bacterial pathogenesis

    Staphylococcus aureus and Staphylococcus epidermidis Virulence Strains as Causative Agents of Persistent Infections in Breast Implants.

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    Staphylococcus epidermidis and Staphylococcus aureus are currently considered two of the most important pathogens in nosocomial infections associated with catheters and other medical implants and are also the main contaminants of medical instruments. However because these species of Staphylococcus are part of the normal bacterial flora of human skin and mucosal surfaces, it is difficult to discern when a microbial isolate is the cause of infection or is detected on samples as a consequence of contamination. Rapid identification of invasive strains of Staphylococcus infections is crucial for correctly diagnosing and treating infections. The aim of the present study was to identify specific genes to distinguish between invasive and contaminating S. epidermidis and S. aureus strains isolated on medical devices; the majority of our samples were collected from breast prostheses. As a first step, we compared the adhesion ability of these samples with their efficacy in forming biofilms; second, we explored whether it is possible to determine if isolated pathogens were more virulent compared with international controls. In addition, this work may provide additional information on these pathogens, which are traditionally considered harmful bacteria in humans, and may increase our knowledge of virulence factors for these types of infections
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