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Pathogenic Microbes (pathogenic + microbe)
Selected AbstractsPathogenic microbes in water and food: changes and challengesFEMS MICROBIOLOGY REVIEWS, Issue 2 2002Thomas Egli No abstract is available for this article. [source] POST-PASTEURIAN CULTURES: The Microbiopolitics of Raw-Milk Cheese in the United StatesCULTURAL ANTHROPOLOGY, Issue 1 2008HEATHER PAXSON ABSTRACT Out of concern for public health, the U.S. government bans the sale of cheese made from unpasteurized milk if it is aged fewer than 60 days. But while the FDA views raw-milk cheese as a potential biohazard, riddled with pathogenic microbes, aficionados see it as the reverse: as a traditional food processed for safety by the action of good microbes. This article offers a theoretical frame for understanding the recent rise in American artisan raw-milk cheese production, as well as wider debates over food localism, nutrition, and safety. Drawing on ethnographic interviews with cheese makers and purveyors and on participant-labor conducted on a Vermont sheep dairy farm, I develop the concept of microbiopolitics to analyze how farmer,cheese makers, industry consultants, retailers, and consumers negotiate Pasteurian (hygienic) and post-Pasteurian (probiotic) attitudes about the microbial agents at the heart of raw-milk cheese and controversies about this nature,culture hybrid. [source] Evasion of macrophage scavenger receptor A-mediated recognition by pathogenic streptococciEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2008Thomas Areschoug Abstract PRR recognize conserved structures on pathogenic microbes and are important for the defense against invading microorganisms. However, accumulating evidence indicates that many pathogens have evolved mechanisms to avoid recognition by PRR. One type of PRR is the macrophage scavenger receptor A (SR-A), which has been shown to play an important role in recognition and non-opsonic phagocytosis of pathogenic bacteria. The bacterial ligands for SR-A have been suggested to be LPS or lipoteichoic acid. Here, we use murine bone marrow-derived macrophages to analyze the role of SR-A in non-opsonic phagocytosis of two major Gram-positive pathogens, Streptococcus agalactiae (group B streptococcus; GBS) and Streptococcus pyogenes. We show that the polysaccharide capsule of GBS and the surface M protein of S. pyogenes, two important virulence factors, prevent SR-A-mediated non-opsonic phagocytosis of streptococci. The sialic acid moiety of the GBS capsule was crucial for its ability to prevent recognition by SR-A. Moreover, we show that a ligand on GBS recognized by SR-A in the absence of capsule is the surface lipoprotein Blr. These findings represent the first example of a microbial strategy to prevent recognition by SR-A and suggest that bacterial surface proteins may be of importance as ligands for SR-A. [source] The generation of nisin variants with enhanced activity against specific Gram-positive pathogensMOLECULAR MICROBIOLOGY, Issue 1 2008Des Field Summary Nisin is the prototype of the lantibiotic group of antimicrobial peptides. It exhibits broad spectrum inhibition of Gram-positive bacteria including important food pathogens and clinically relevant antibiotic-resistant bacteria. Significantly, the gene-encoded nature of nisin means that it can be subjected to gene-based bioengineering to generate novel derivatives. Here, we take advantage of this to generate the largest bank of randomly mutated nisin derivatives reported to date, with the ultimate aim of identifying variants with enhanced bioactivity. This approach led to the identification of a nisin-producing strain with enhanced bioactivity against the mastitic pathogen Streptococcus agalactiae resulting from an amino acid change in the hinge region of the peptide (K22T). Prompted by this discovery, site-directed and site-saturation mutagenesis of the hinge region residues was employed, resulting in the identification of additional derivatives, most notably N20P, M21V and K22S, with enhanced bioactivity and specific activity against Gram-positive pathogens including Listeria monocytogenes and/or Staphylococcus aureus. The identification of these derivatives represents a major step forward in the bioengineering of nisin, and lantibiotics in general, and confirms that peptide engineering can deliver derivatives with enhanced antimicrobial activity against specific problematic spoilage and pathogenic microbes or against Gram-positive bacteria in general. [source] Pantoea ananatis: an unconventional plant pathogenMOLECULAR PLANT PATHOLOGY, Issue 3 2009TERESA A. COUTINHO SUMMARY Pantoea ananatis causes disease symptoms in a wide range of economically important agricultural crops and forest tree species worldwide. It is regarded as an emerging pathogen based on the increasing number of reports of diseases occurring on previously unrecorded hosts in different parts of the world. Its unconventional nature lies in the fact that, unlike the majority of plant pathogenic microbes, P. ananatis is capable of infecting humans and occurs in diverse ecological niches, such as part of a bacterial community contaminating aviation jet fuel tanks and contributing to growth promotion in potato and pepper. Taxonomy: Bacteria; Gammaproteobacteria; family Enterobacteriaceae; genus Pantoea. Microbiological properties: Gram-negative; facultatively anaerobic; most strains are motile and produce a yellow pigment in culture; indole positive. Biology:Pantoea ananatis is a common epiphyte; it also occurs endophytically in hosts where it has been reported to cause disease symptoms and in hosts where no such symptoms have been described. Some strains are ice-nucleating, a feature which has been used as a biological control mechanism against some insect pests of agricultural crops and by the food industry. Disease symptoms:Pantoea ananatis infects both monocotyledonous and dicotyledonous plants. The symptoms are diverse depending on the host infected, and include leaf blotches and spots, die-back, and stalk, fruit and bulb rot. Biological control agent:Pantoea ananatis has both antifungal and antibacterial properties. These characteristics have the potential of being exploited by biological control specialists. [source] Antigen Presentation by Human Uterine Epithelial Cells to Autologous T CellsAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2006John V. Fahey Problem, Epithelial cells, as sentinels of immune protection in the endometrium, use innate immune mechanisms to protect against infection from pathogenic microbes. Our goal in this study was to assess the ability of human uterine epithelial cells to present antigen to cells of the adaptive immune system. Method of study, Highly purified preparations of uterine epithelial cells from 11 patients were assessed for their ability to present tetanus toxoid (TT) to autologous T cells. Leukocyte contamination in the epithelial cell preparations was numerically and functionally determined. Using confocal microscopy, epithelial cells were tested for the expression of CD40 and CD1d. Results, Purified preparations of endometrial epithelial cells isolated from every patient presented TT recall antigen to autologous T cells. Leukocyte contamination of epithelial cell preparations was insignificant. Uterine epithelial cells express CD40 and CD1d. Conclusion, Antigen presentation is an additional aspect of uterine epithelial cell function in maintaining women's health. [source] Scavenger receptors: role in innate immunity and microbial pathogenesisCELLULAR MICROBIOLOGY, Issue 8 2009Thomas Areschoug Summary Accumulating evidence shows that many scavenger receptors (SR), including SR-A, MARCO and CD36, represent an important part of the innate immune defence by acting as pattern-recognition receptors, in particular against bacterial pathogens. Several SR are expressed on macrophages and dendritic cells, where they act as phagocytic receptors mediating non-opsonic phagocytosis of pathogenic microbes. Another important function of some SR is to act as co-receptors to Toll-like receptors (TLR), modulating the inflammatory response to TLR agonists. On bacteria, the SR ligands have commonly been reported to be lipopolysaccharide and lipoteichoic acid, but recent advances in the field indicate that bacterial surface proteins play a more important role as target molecules for SR than previously thought. Interestingly, recent data show that major pathogens, including Streptococcus pyogenes and the group B streptococcus, have evolved mechanisms to evade SR-mediated recognition. Moreover, intracellular pathogens, such as hepatitis C virus and Plasmodium falciparum, utilize the SR to gain entry into host cells, focusing interest on the importance of SR also in the molecular pathogenesis of infectious diseases. This review highlights the complex interactions between SR and pathogenic microbes, and discusses the role of these interactions in host defence and microbial pathogenesis. [source] How important are Toll-like receptors for antimicrobial responses?CELLULAR MICROBIOLOGY, Issue 8 2007Susan Carpenter Summary The innate immune system is the primary line of defence against invading pathogenic microbes. Toll-like receptors (TLRs) are a family of membrane receptors which play a pivotal role in sensing a wide range of invading pathogens including bacteria, fungi and viruses. TLR-deficient mice have provided us with immense knowledge on the functioning of individual TLRs. Dysregulation of TLR signalling is linked with a number of disease conditions. Disease models have helped show that targeting components of TLR signalling cascades could lead to novel therapies in the treatment of infectious diseases. In this review we focus on the evidence provided to date to explain just how important TLRs are in host defence against microbial pathogens. [source] | |||||||||||||