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Opportunistic Pathogen (opportunistic + pathogen)
Selected AbstractsProblems of Developing Molecular Diagnostic Tests for Opportunistic Pathogens: The Example of Pneumocystis jiroveciiTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2006JIM F. HUGGETT [source] A molecular biological protocol to distinguish potentially human pathogenic Stenotrophomonas maltophilia from plant-associated Stenotrophomonas rhizophilaENVIRONMENTAL MICROBIOLOGY, Issue 11 2005Kathrin Ribbeck-Busch Summary In recent years, the importance of the Gram-negative bacterium Stenotrophomonas as an opportunistic pathogen as well as in biotechnology has increased. The aim of the present study was to develop new methods for distinguishing between strains closely related to the potentially human pathogenic Stenotrophomonas maltophilia and those closely related to the plant-associated Stenotrophomonas rhizophila. To accomplish this, 58 strains were characterized by 16S rDNA sequencing and amplified ribosomal DNA restriction analysis (ARDRA), and the occurrence of specific functional genes. Based on 16S rDNA sequences, an ARDRA protocol was developed which allowed differentiation between strains of the S. maltophilia and the S. rhizophila group. As it was known that only salt-treated cells of S. rhizophila were able to synthesize the compatible solute glucosylglycerol (GG), the ggpS gene responsible for GG synthesis was used for differentiation between both species and it was confirmed that it only occurred in S. rhizophila strains. As a further genetic marker the smeD gene, which is part of the genes coding for the multidrug efflux pump SmeDEF from S. maltophilia, was used. Based on the results we propose a combination of fingerprinting techniques using the 16S rDNA and the functional genes ggpS and smeD to distinguish both Stenotrophomonas species. [source] Innate, antigen-independent role for T cells in the activation of the immune system by Propionibacterium acnesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 9 2010Sandrine Tchaptchet Abstract Propionibacterium acnes is a human commensal but also an opportunistic pathogen. In mice, P. acnes exerts strong immunomodulatory activities, including formation of intrahepatic granulomas and induction of LPS hypersensitivity. These activities are dependent on P. acnes recognition via TLR9 and subsequent IL-12-mediated IFN-, production. We show that P. acnes elicits IL-12p40 and p35 mRNA expression in macrophages, and IFN-, mRNA in liver CD4+ T cells and NK cells. After priming with P. acnes, CD4+ T cells serve as the major IFN-, mRNA source. In the absence of CD4+ T cells, CD8+ T cells (regardless of antigenic specificity) or NK cells can produce sufficient IFN-, to induce the P. acnes -driven immune effects. Moreover, in the absence of ,,T cells, ,,T cells also enable the development of strongly enhanced TNF-, and IFN-, responses to LPS and intrahepatic granuloma formation. Thus, under microbial pressure, different T-cell types, independent of their antigen specificity, exert NK-cell-like functions, which contribute decisively to the activation of the innate immune system. [source] In vitro Study of the Antibacterial Activity of Bioactive Glass-ceramic Scaffolds,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Marta F. Gorriti Staphylococcus aureus is an opportunistic pathogen of major clinical interest for its high prevalence in biomaterial-related infections. This experimental study provides the first evidence in vitro that bioactive glass-ceramic scaffolds made from both 45S5 Bioglass® and from boron containing bioactive glass (45S5.2B) as well as their ionic dissolution products do no exhibit antibacterial effect against several strains of S. aureus. [source] Effect of suramin on the human pathogen Candida albicans: implications on the fungal development and virulenceFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2007Lys Adriana Braga-Silva Abstract Candida albicans is an opportunistic pathogen that is of growing medical importance because it causes superficial, mucosal and systemic infections in susceptible individuals. Here, the effect of suramin, a polysulfonated naphthylurea derivative, on C. albicans development and virulence was evaluated. Firstly, it was demonstrated that suramin (500 ,M) arrested its growth, showing a fungicidal action dependent on cell number. Suramin treatment caused profound changes in the yeast ultrastructure as shown by transmission electron microscopy. The more important changes were the enlargement of the fungi cytoplasmic vacuoles, the appearance of yeasts with an empty cytoplasm resembling ghost cells and a reduction in cell wall thickness. Suramin also blocked the transformation of yeast cells to the germ-tube and the interaction between C. albicans and epithelial cells. In order to ascertain that the action of suramin on C. albicans growth is a general feature instead of being strain-specific, the effects of suramin on 14 oral clinical strains isolated from healthy children and HIV-positive infants were analyzed. Interestingly, the strains of C. albicans isolated from HIV-positive patients were more resistant to suramin than strains isolated from healthy patients. Altogether, the results produced here show that suramin interfered with essential fungal processes, such as growth, differentiation and interaction with host cells. [source] Antagonistic activity of Aeromonas media strain A199 against Saprolegnia sp., an opportunistic pathogen of the eel, Anguilla australis RichardsonJOURNAL OF FISH DISEASES, Issue 3 2003M J Lategan Abstract A bacteriocin-like inhibitory substance (BLIS) produced by Aeromonas media strain A199 inhibited the growth of Saprolegnia sp. in vitro, an opportunistic pathogen isolated from affected eels, Anguilla australis (Richardson). The presence of BLIS in solid media inhibited the growth of the vegetative state of the aquatic mould as well as the germination of cysts. Uninhibited growth was, however, observed in the presence of inactive BLIS, suggesting that the in vitro antagonism derived from the BLIS of A199. In four independent in vivo tank observations of fish affected with saprolegniosis, the daily addition of A199 to tank water contributed to the subsequent swift recovery of affected hosts from invasion by this opportunistic pathogen. [source] Cronobacter (,Enterobacter sakazakii'): current status and future prospectsLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2009J.W. Chenu Abstract The genus Cronobacter accommodates the 16 biogroups of the emerging opportunistic pathogen known formerly as Enterobacter sakazakii. Cronobacter spp. are occasional contaminants of milk powder and, consequently, powdered infant formula and represent a significant health risk to neonates. This review presents current knowledge of the food safety aspects of Cronobacter, particularly in infant formula milk powder. Sources of contamination, ecology, disease characteristics and risk management strategies are discussed. Future directions for research are indicated, with a particular focus on the management of this increasingly important bacterium in the production environment. [source] Cell wall ,-1,3-glucan is required to anchor the Cryptococcus neoformans capsuleMOLECULAR MICROBIOLOGY, Issue 4 2003Amy J. Reese Summary Cryptococcus neoformans is an opportunistic pathogen responsible for serious disease in humans. Critical for virulence of this fungus is an elaborate polysaccharide capsule, which impedes the host immune response. We found that association of the capsule with the cell requires a specific component of the cell wall, ,-1,3-glucan. Post-transcriptional inhibition of ,-1,3-glucan synthase expression, using double-stranded RNA interference, yields cells that are unable to assemble a capsule although they generate its polysaccharide components. The resulting cryptococci are slow-growing and acapsular. This finding demonstrates a novel mode of polysaccharide attachment and an important application of RNA interference in fungi. The elimination of the capsule by reducing the expression of a single gene suggests a potential avenue for antifungal chemotherapy. [source] The protein secretory pathway of Candida albicansMYCOSES, Issue 4 2009William A. Fonzi Summary Virulence of the opportunistic pathogen, Candida albicans, relies on an assemblage of attributes. These include the secretion of hydrolytic enzymes, cell surface adhesins, morphological transition between yeast and hyphae, phenotypic switching and biofilm formation. These diverse features are united by their dependence on the protein secretory apparatus for expression. Although the secretory apparatus of C. albicans has been studied limitedly, it appears to conform to the well-conserved eukaryotic system of vesicle-mediated transport between intracellular compartments and the cell surface. Genome comparison with Saccharomyces cerevisiae, however, shows multiple differences whose functional significance is yet unstudied. A unique aspect of the secretory pathway of C. albicans is its structural, and perhaps functional, rearrangement in hyphal vs. yeast cells. This, and evidence of non-conserved secretion mechanism(s), suggest that there is much fundamental knowledge to be derived from the analysis of secretion in C. albicans, which will be relevant to its ability to cause disease. [source] Analysis of the periplasmic proteome of Pseudomonas aeruginosa, a metabolically versatile opportunistic pathogenPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 7 2009Francesco Imperi Abstract The Gram-negative bacterium Pseudomonas aeruginosa is a main cause of infection in hospitalized, burned, immunocompromised, and cystic fibrosis patients. Many processes essential for P. aeruginosa pathogenesis, e.g., nutrient uptake, antibiotic resistance, and virulence, take place in the cell envelope and depend on components residing in the periplasmic space. Recent high-throughput studies focused on P. aeruginosa membrane compartments. However, the composition and dynamics of its periplasm remain largely uncharacterized. Here, we report a detailed description of the periplasmic proteome of the wild-type P. aeruginosa strain PAO1 by 2-DE and MALDI-TOF/TOF analysis. Three extraction methods were compared at proteome level in order to achieve the most reliable and comprehensive periplasmic protein map. A total of 495 spots representing 395 different proteins were identified. Most of the high intensity spots corresponded to periplasmic proteins, while cytoplasmic contaminants were mainly detected among faint spots. The majority of the identified periplasmic proteins is involved in transport, cell-envelope integrity, and protein folding control. Notably, more than 30% still has an unpredicted function. This work provides the first overview of the P. aeruginosa periplasm and offers the basis for future studies on periplasmic proteome changes occurring during P. aeruginosa adaptation to different environments and/or antibiotic treatments. [source] Crystallization and preliminary X-ray analysis of the human-specific toxin intermedilysinACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2004Galina Polekhina Intermedilysin is a human-specific toxin from Streptococcus intermedius, which is part of normal human oral flora. The bacterium is an opportunistic pathogen with a tendency for deep-seated infection in the brain and liver. Intermedilysin belongs to the cholesterol-dependent cytolysin (CDCs) family of toxins, which have been identified in several different bacteria including the serious human pathogens S. pneumoniae and Clostridium perfringens. Intermedilysin, however, is the only member that shows exclusive specificity for human cells. The toxin has a couple of non-conservative amino-acid substitutions in a tryptophan-rich region of the molecule (Cys to Ala and Trp to Pro), the most conserved region amongst the CDCs. Mutations in this region are known to render other CDCs inactive. In order to investigate the structure,function relationships of the unusual features of intermedilysin, which will help us to understand the molecular mechanism of the toxin family in general, recombinant intermedilysin has been crystallized. The crystals belong to an orthorhombic space group and contain two molecules per asymmetric unit. Diffraction data were collected to 2.3,Å using synchrotron radiation. [source] Structure of Stenotrophomonas maltophilia FeoA complexed with zinc: a unique prokaryotic SH3-domain protein that possibly acts as a bacterial ferrous iron-transport activating factorACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2010Yi-Che Su Iron is vital to the majority of prokaryotes, with ferrous iron believed to be the preferred form for iron uptake owing to its much better solubility. The major route for bacterial ferrous iron uptake is found to be via an Feo (ferrous iron-transport) system comprising the three proteins FeoA, FeoB and FeoC. Although the structure and function of FeoB have received much attention recently, the roles played by FeoA and FeoC have been little investigated to date. Here, the tertiary structure of FeoA from Stenotrophomonas maltophilia (Sm), a vital opportunistic pathogen in immunodepressed hosts, is reported. The crystal structure of SmFeoA has been determined to a resolution of 1.7,Å using an Se single-wavelength anomalous dispersion (Se-SAD) approach. Although SmFeoA bears low sequence identity to eukaryotic proteins, its structure is found to adopt a eukaryotic SH3-domain-like fold. It also bears weak similarity to the C-terminal SH3 domain of bacterial DtxR (diphtheria toxin regulator), with some unique characteristics. Intriguingly, SmFeoA is found to adopt a unique dimer cross-linked by two zinc ions and six anions (chloride ions). Since FeoB has been found to contain a G-protein-like domain with low GTPase activity, FeoA may interact with FeoB through the SH3,G-protein domain interaction to act as a ferrous iron-transport activating factor. [source] Crystallization and preliminary X-ray diffraction characterization of RpfF, a key DSF synthase from Stenotrophomonas maltophiliaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2009Xian-Ya Lin Stenotrophomonas maltophilia has emerged as a critical nosocomial opportunistic pathogen in the last few years. It is resistant to many clinically useful antibiotics; hence, new ways of combatting this bacterium are essential. Diffusible signal factor (DSF) dependent quorum sensing is a major mechanism of virulence induction in S. maltophilia, with RpfF playing a key role in DSF biosynthesis. Inhibiting S. maltophilia RpfF (SmRpfF) function via small-molecule interference may constitute a new way of treating S. maltophilia infection. SmRpfF was therefore overexpressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The crystals belonged to the tetragonal space group P41212 or P43212, with unit-cell parameters a = b = 148.51, c = 122.82,Å, and diffracted to a resolution of 2.25,Å. [source] The purification, crystallization and preliminary structural characterization of FAD-dependent monooxygenase PhzS, a phenazine-modifying enzyme from Pseudomonas aeruginosaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2006Neelakshi Gohain The blue chloroform-soluble bacterial metabolite pyocyanin (1-hydroxy-5-methyl-phenazine) contributes to the survival and virulence of Pseudomonas aeruginosa, an important Gram-negative opportunistic pathogen of humans and animals. Little is known about the two enzymes, designated PhzM and PhzS, that function in the synthesis of pyocyanin from phenazine-1-carboxylic acid. In this study, the FAD-dependent monooxygenase PhzS was purified and crystallized from lithium sulfate/ammonium sulfate/sodium citrate pH 5.5. Native crystals belong to space group C2, with unit-cell parameters a = 144.2, b = 96.2, c = 71.7,Å, , = , = 90, , = 110.5°. They contain two monomers of PhzS in the asymmetric unit and diffract to a resolution of 2.4,Å. Seleno- l -methionine-labelled PhzS also crystallizes in space group C2, but the unit-cell parameters change to a = 70.6, b = 76.2, c = 80.2,Å, , = , = 90, , = 110.5° and the diffraction limit is 2.7,Å. [source] The purification, crystallization and preliminary structural characterization of PhzM, a phenazine-modifying methyltransferase from Pseudomonas aeruginosaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2006Neelakshi Gohain Pyocyanin, phenazine-1-carboxylic acid and more than 70 related compounds collectively known as phenazines are produced by various species of Pseudomonas, including the fluorescent pseudomonad P. aeruginosa, a Gram-negative opportunistic pathogen in humans and animals. P. aeruginosa synthesizes a characteristic blue water-soluble compound called pyocyanin (1-hydroxy-5-methyl-phenazine). Two enzymes designated PhzM and PhzS are involved in the terminal steps of its synthesis and very little is known about these enzymes. In this study, PhzM, a dimeric S -adenosylmethionine-dependent methyltransferase, was purified and crystallized from PEG 3350/sodium cacodylate/sodium citrate pH 6.5. The crystals belong to space group P1, with unit-cell parameters a = 46.1, b = 61.8, c = 69.6,Å, , = 96.3, , = 106.6, , = 106.9°. They contain one dimer in the asymmetric unit and diffract to a resolution of 1.8,Å. Anomalous data to 2.3,Å resolution have been collected from seleno- l -methionine-labelled PhzM. [source] Host responses to a versatile commensal: PAMPs and PRRs interplay leading to tolerance or infection by Candida albicansCELLULAR MICROBIOLOGY, Issue 7 2009Thierry Jouault Summary The molecular interactions between commensal microorganisms and their host are basically different from those triggered by pathogens since they involve tolerance. When the commensal is genetically equipped to become an opportunistic pathogen, as is the case with Candida albicans, the picture becomes more complex. In this case, the balance between protection and invasion depends on host reactivity to altered microbial expression of ligands interacting with innate immune sensors. Based on experimental evidence obtained with C. albicans, we discuss the different molecular processes involved in the sensing of this important opportunistic human pathogen by a panel of pattern recognition receptors (PRRs) according to the numerous pathogen-associated molecular patterns (PAMPs) that can be exposed at its surface. Beneficial or deleterious immune responses that either maintain a commensal state or favour damage by the yeast result from this dynamic interplay. [source] Full Structure of the Carbohydrate Chain of the Lipopolysaccharide of Providencia rustigianii,O34CHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2008Abstract A lipopolysaccharide isolated from an opportunistic pathogen of the Enterobacteriaceae family Providencia rustigianii,O34 was found to be a mixture of R-, SR-, and S - forms consisting of a lipid moiety (lipid,A) that bears a core oligosaccharide, a core with one O-polysaccharide repeating unit attached, and a long-chain O-polysaccharide, respectively. The corresponding carbohydrate moieties were released from the lipopolysaccharide by mild acid hydrolysis and studied by sugar and methylation analyses along with one- and two-dimensional NMR spectroscopy and high-resolution electrospray ionization mass spectrometry. As a result, the structures of the core and the O-polysaccharide were established, including the structure of the biological repeating unit (an oligosaccharide that is preassembled and polymerized in biosynthesis of the O-polysaccharide), as well as the mode of the linkage between the O-polysaccharide and the core. Combining the structure of the carbohydrate moiety thus determined and the known structure of lipid,A enabled determination of the full lipopolysaccharide structure of P. rustigianii,O34. [source] Microbiological and clinical features of Corynebacterium urealyticum: urinary tract stones and genomics as the Rosetta StoneCLINICAL MICROBIOLOGY AND INFECTION, Issue 7 2008F. Soriano Abstract Corynebacterium urealyticum, formerly known as coryneform CDC group D2, was first recognized to be involved in human infections 30 years ago. It is a slow-growing, lipophilic, asaccharolytic and usually multidrug-resistant organism with potent urease activity. Its cell wall peptidoglycan, menaquinone, mycolic and cellular fatty acid composition is consistent with that of the genus Corynebacterium. DNA,DNA hybridization studies and 16S rDNA sequencing analysis have been used to determine the degree of relatedness of C. urealyticum to other corynebacterial species. The genome of the type strain consists of a circular chromosome with a size of 2 369 219 bp and a mean G + C content of 64.2%, and analysis of its genome explains the bacterium's lifestyle. C. urealyticum is a common skin colonizer of hospitalized elderly individuals who are receiving broad-spectrum antibiotics. It is an opportunistic pathogen causing mainly acute cystitis, pyelonephritis, encrusted cystitis, and encrusted pyelitis. More infrequently, it causes other infections, but mainly in patients with urological diseases. Infections are more common in males than in females, and treatment requires administration of antibiotics active against the organism in vitro, mainly glycopeptides, as well as surgical intervention, the latter mostly in cases of chronic infection. Mortality directly associated with infection by this organism is not frequent, but encrusted pyelitis in kidney-recipient patients may cause graft loss. The outcome of infection by this organism is reasonably good if the microbiological diagnosis is made and patients are treated appropriately. [source] Development of a bacterial challenge test for gnotobiotic sea bass (Dicentrarchus labrax) larvaeENVIRONMENTAL MICROBIOLOGY, Issue 2 2009K. Dierckens Summary The use of probiotic microorganisms in aquaculture is gaining a lot of interest. Gnotobiotic model systems are required in order to fully understand the effects and modes-of-action of these microorganisms, as the native microbial communities present in non-sterile animals can lead to false conclusions. In this study, a gnotobiotic sea bass larvae (Dicentrarchus labrax) test system was developed. In order to obtain bacteria-free animals, the eggs were disinfected with glutaraldehyde and subsequently incubated in a solution of rifampicin and ampicillin. Axenity was confirmed using culture-dependent and -independent techniques. The gnotobiotic larvae were fed axenic Artemia sp. from 7 days after hatching onwards. In the challenge test, one of the three opportunistic pathogens, Aeromonas hydrophila, Listonella anguillarum serovar O1 and O2a, was added to the model system via the water and encapsulated in Artemia sp. Only serovar O2a led to increased mortality in the sea bass larvae. The presented gnotobiotic model can be used for research on, among others, reciprocal metabolic effects between microorganisms and the host (e.g. as measured by gene expression), immunostimulants, pharmacological research and the histological development of the gastrointestinal tract and growth of larvae. [source] Investigating Burkholderia cepacia complex populations recovered from Italian maize rhizosphere by multilocus sequence typingENVIRONMENTAL MICROBIOLOGY, Issue 7 2007Claudia Dalmastri Summary The Burkholderia cepacia complex (BCC) comprises at least nine closely related species of abundant environmental microorganisms. Some of these species are highly spread in the rhizosphere of several crop plants, particularly of maize; additionally, as opportunistic pathogens, strains of the BCC are capable of colonizing humans. We have developed and validated a multilocus sequence typing (MLST) scheme for the BCC. Although widely applied to understand the epidemiology of bacterial pathogens, MLST has seen limited application to the population analysis of species residing in the natural environment; we describe its novel application to BCC populations within maize rhizospheres. 115 BCC isolates were recovered from the roots of different maize cultivars from three different Italian regions over a 9-year period (1994,2002). A total of 44 sequence types (STs) were found of which 41 were novel when compared with existing MLST data which encompassed a global database of 1000 clinical and environmental strains representing nearly 400 STs. In this study of rhizosphere isolates approximately 2.5 isolates per ST was found, comparable to that found for the whole BCC population. Multilocus sequence typing also resolved inaccuracies associated with previous identification of the maize isolates based on recA gene restriction fragment length polymorphims and species-specific polymerase chain reaction. The 115 maize isolates comprised the following BCC species groups, B. ambifaria (39%), BCC6 (29%), BCC5 (10%), B. pyrrocinia (8%), B. cenocepacia IIIB (7%) and B. cepacia (6%), with BCC5 and BCC6 potentially constituting novel species groups within the complex. Closely related clonal complexes of strains were identified within B. cepacia, B. cenocepacia IIIB, BCC5 and BCC6, with one of the BCC5 clonal complexes being distributed across all three sampling sites. Overall, our analysis demonstrates that the maize rhizosphere harbours a massive diversity of novel BCC STs, so that their addition to our global MLST database increased the ST diversity by 10%. [source] The rhizosphere as a reservoir for opportunistic human pathogenic bacteriaENVIRONMENTAL MICROBIOLOGY, Issue 11 2005Gabriele Berg Summary During the last years, the number of human infections caused by opportunistic pathogens has increased dramatically. One natural reservoir of opportunistic pathogens is the rhizosphere, the zone around roots that is influenced by the plant. Due to a high content of nutrients, this habitat is a ,microbial hot-spot', where bacterial abundances including those with strong antagonistic traits are enhanced. Various bacterial genera, including Burkholderia, Enterobacter, Herbaspirillum, Ochrobactrum, Pseudomonas, Ralstonia, Staphylococcus and Stenotrophomonas, contain root-associated strains that can encounter bivalent interactions with both plant and human hosts. Mechanisms responsible for colonization of the rhizosphere and antagonistic activity against plant pathogens are similar to those responsible for colonization of human organs and tissues, and pathogenicity. Multiple resistances against antibiotics are not only found with clinical strains but also with strains isolated from the rhizosphere. High competition, the occurrence of diverse antibiotics in the rhizosphere, and enhanced horizontal gene transfer rates in this microenvironment appear to contribute to the high levels of natural resistances. While opportunistic bacteria from the rhizosphere have some properties in common, each of these emerging pathogens has its own features, which are discussed in detail for Burkholderia, Ochrobactrum and Stenotrophomonas. [source] Surrounded by mycobacteria: nontuberculous mycobacteria in the human environmentJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2009J.O. Falkinham Summary A majority of the Mycobacterium species, called the nontuberculous mycobacteria (NTM), are natural inhabitants of natural waters, engineered water systems, and soils. As a consequence of their ubiquitous distribution, humans are surrounded by these opportunistic pathogens. A cardinal feature of mycobacterial cells is the presence of a hydrophobic, lipid-rich outer membrane. The hydrophobicity of NTM is a major determinant of aerosolization, surface adherence, biofilm-formation, and disinfectant- and antibiotic resistance. The NTM are oligotrophs, able to grow at low carbon levels [>50 ,g assimilable organic carbon (AOC) l,1], making them effective competitors in low nutrient, and disinfected environments (drinking water). Biofilm formation and oligotrophy lead to survival, persistence, and growth in drinking water distribution systems. In addition to their role as human and animal pathogens, the widespread distribution of NTM in the environment, coupled with their ability to degrade and metabolize a variety of complex hydrocarbons including pollutants, suggests that NTM may be agents of nutrient cycling. [source] Allen Denver Russell Memorial Lecture, 2006JOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2006The use of microbiocides in infection control: a critical look at safety, applications, testing Abstract Microbial pathogens continue as major threats to health. Indeed, many ongoing societal changes are enhancing our vulnerability and exposure to several frank and opportunistic pathogens. This, together with rampant antimicrobial resistance and reduced prospects for newer drugs and vaccines, is forcing a higher reliance on microbiocides in infection prevention and control. That this reliance may not be well-founded becomes apparent from a closer look at current ways of testing and registering microbiocides, their label claims as well as human and environmental safety of certain widely used microbicidal chemicals. Many methods to test microbiocides for registration are flawed and/or entail test conditions irrelevant to field use. Pathogens listed on product labels may not be among those amenable to interruption through microbiocide use. The wide variations and discrepancies in existing national/regional regulations for registering microbiocides for sale stifle innovation. This is a critical look at the above-mentioned issues with emphasis on chemicals meant for use on environmental surfaces and medical devices. It highlights better ways to test microbiocides and to attain global harmonization of testing and product registration. It also details the known and potential dangers of microbiocide use and what to consider in choosing such formulations for optimal safety and effectiveness. End users are advised to be more critical and prudent in the selection and application of microbicidal chemicals, manufacturers are encouraged to explore infection control products and technologies that are safer in the workplace and for the environment, and regulators are urged to review and update the requirements and procedures for premarket review of microbiocide efficacy data and label claims. Independent investigations are also urgently needed to document the proportion of nosocomial infections that would be amenable to prevention through chemical disinfection of environmental surfaces. [source] Naturally occurring bacteraemia in American lobsters, Homarus americanus Milne-Edwards, in Long Island SoundJOURNAL OF FISH DISEASES, Issue 1 2008S L Bartlett Abstract The health status of the American lobster, Homarus americanus Milne-Edwards, in Long Island Sound (LIS) has been in decline, with seasonal mortality events occurring since 1998. In order to assess the potential effects of environmental conditions on lobster health via haemolymph analysis, lobsters collected from various sites in LIS were examined and sampled while concurrent environmental data (water temperature, salinity and dissolved oxygen) were recorded. The pH of the haemolymph of each lobster was tested, followed by a collection of haemolymph for serum biochemistry analysis and bacterial culture. This report focuses on the results of the bacterial sampling. The majority of bacteria cultured were opportunistic pathogens commonly found in the environment, including some that are associated with sewage and pollution. The prevalence of bacteraemia was correlated with the site of collection, the month in which the lobsters were sampled, and water temperature. [source] Patterns of Multiple Virus Infections in the Conifer Pathogenic Fungi, Diplodia pinea and Diplodia scrobiculataJOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2008Juanita De Wet Abstract Diplodia pinea and Diplodia scrobiculata are opportunistic pathogens associated with various disease symptoms on conifers that most importantly include die-back and stem cankers. Two viruses with dsRNA genomes, Sphaeropsis sapinea RNA virus 1 and 2 (SsRV1 and SsRV2) are found in D. pinea and an undescribed dsRNA element is known to occur in D. scrobiculata. We have partially characterized the putative RNA-dependent RNA polymerase (RdRp) of the undescribed dsRNA element and designed virus-specific primers from the RdRp regions of all three virus genomes. This made it possible to screen for the presence of the three viruses in a collection of D. pinea and D. scrobiculata isolates using real-time PCR. Triple infections with all three viruses occurred in D. pinea and D. scrobiculata. Co-infections with SsRV1 and SsRV2 were common but found only in D. pinea. Co-infection with SsRV1 and the undescribed dsRNA element was rare and observed only in D. pinea. Single infections with either SsRV1 or SsRV2 were equally common, while the undescribed dsRNA element never occurred alone. SsRV1 occurred alone in both D. pinea and D. scrobiculata while SsRV2 occurred alone only in D. pinea. There were only two instances where the undescribed dsRNA element was observed in D. pinea and it was otherwise found only in D. scrobiculata. This study highlights the complex interactions between the viruses found in the closely related plant pathogenic fungi, D. pinea and D. scrobiculata. It illustrates the importance of not only characterizing viruses infecting fungi but also of determining the interactions between mycoviruses and their fungal hosts. [source] Congenital rubella pneumonitis complicated by Pneumocystis jiroveci infection with positive long term respiratory outcome: A case report and literature reviewPEDIATRIC PULMONOLOGY, Issue 12 2009M.O. Sanchez MD Abstract Rubella remains to be a significant illness in the developing countries because of limited access to immunizations. In congenital rubella syndrome, lung involvement becomes evident within the few months of life, as a manifestation of the "late onset rubella syndrome." The lungs and other organs become involved secondary to immunopathologic mechanisms and immunodeficiency predisposes affected patients to opportunistic pathogens. We report the clinical, respiratory and immunologic data of a young boy who developed rubella pneumonitis and concomitant infection with Pneumocystis jiroveci. Despite the complicated clinical course, the child survived. At follow-up he has a normal pulmonary examination, mild hyperinflation only on his chest radiograph, normal immunology and normal respiratory reactance and resistance. Pediatr Pulmonol. 2009; 44:1235,1239. © 2009 Wiley-Liss, Inc. [source] Potato diseases caused by soft rot erwinias: an overview of pathogenesisPLANT PATHOLOGY, Issue 1 2002M. C. M. Pérombelon Three soft rot erwinias, Erwinia carotovora ssp. carotovora, E. carotovora ssp. atroseptica and E. chrysanthemi are associated with potatoes causing tuber soft rot and blackleg (stem rot). Latent infection of tubers and stems is widespread. As opportunistic pathogens, the bacteria tend to cause disease when potato resistance is impaired. Pathogenesis or disease development in potato tubers and stems is discussed in terms of the interaction between pathogen, host and environment, microbial competition and recent findings on the molecular basis of pathogenicity. Emphasis is placed on the role of free water and anaerobiosis in weakening tuber resistance and in providing nutrient for erwinias to multiply. Blackleg symptoms are expressed when erwinias predominate in rotting mother tubers, invade the stems and multiply in xylem vessels under favourable weather conditions. Soft rot erwinias tend to out-compete other bacteria in tuber rots because of their ability to produce larger quantities of a wider range of cell wall-degrading enzymes. However, despite extensive studies on their induction, regulation and secretion, little is known about the precise role of the different enzymes in pathogenesis. The putative role of quorum-sensing regulation of these enzymes in disease development is evaluated. The role certain pathogenicity-related characters, including motility, adhesion, siderophores, detoxifying systems and the hrp gene complex, common to most bacteria including symbionts and saprophytes, could play in latent and active infections is also discussed. [source] Isolation of a Thermotolerant Paravahlkampfia sp. from Lizard Intestine: Biology and Molecular IdentificationTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 5 2003FREDERICK L. SCHUSTER ABSTRACT. An amoeba was isolated from the intestines of several moribund pink-tongued skinks (lizards), Hemisphaeriodon ger-rardi Unusual features of this isolate were its ability to grow at temperatures of , 37 °C, and its inability to use Escherichia coli as a food source or to grow axenically on a variety of enriched culture media suitable for other soil amoeba isolates. Growth was abundant, however, on tissue culture cells, with amoebae clearing cell monolayers in ,48 h at 37 °C. Trophozoites had a vahlkampfiid-like morphology, moving by means of an anterior eruptive pseudopod. Cysts, round to slightly ovoid and lacking exit pores, were formed in culture. Tests for enflagellation of trophic amoebae were negative. Indirect immunofluorescence staining was negative for Naegleria fowleri and Willaertia sp. The isolate was sensitive to azithromycin, but not to amphotericin B, pentamidine isethionate, fluconazole, 5-fluorocytosine, and sulfadiazine. Phylogenetic analysis based on the PCR-amplified small subunit ribosomal DNA, identified the organism as Paravahlkampfia ustiana, an amoeba not previously isolated from either poikilothermic or homeothermic hosts. No evidence of pathology was seen in stained sections of lizard intestine, suggesting that the ameba was part of the normal fauna of the lizard gut. Its diet in the lizard intestine is unknown and the organism may have unusual growth requirements. Thus, P. ustiana joins other soil amoebae that have been isolated from mammals, amphibia, fish, and reptiles, which have the potential of becoming opportunistic pathogens. [source] Ingestion of multiple veterinary drugs and associated impact on vulture health: implications of livestock carcass elimination practicesANIMAL CONSERVATION, Issue 6 2009G. Blanco Abstract Veterinary drugs present in livestock carcasses may be ingested by scavengers and may cause important declines in their populations, as reported for diclofenac in Asia. Drug content of carcasses may depend on the prevailing livestock operations and legal regulations for carcass elimination. In Spain, the main stronghold of vultures in Europe, legal measures to mitigate the spread of bovine spongiform encephalopathy (BSE) have caused the lack or scarcity of unstabled livestock carcasses available for avian scavengers, and the parallel increase in use of dumps of livestock carcasses supplied by farms, especially of intensively medicated pigs and poultry. We evaluated temporal trends in the presence and concentration of antibiotics and other veterinary drugs, and their associated health impacts on three vulture species, due to the ban of abandoning unstabled livestock carcasses in the countryside since the BSE crisis. An increasing presence and concentration of antibiotics since the BSE crisis, and residues of three non-steroidal anti-inflammatories (NSAIDs) and four anti-parasitics were found in the vultures. Quinolones were associated with infection by opportunistic pathogens in the three species and with generalized damage to internal organs in the cinereous vulture, but no clear health impacts of NSAIDs and anti-parasitics were found. Given that there is no evidence of BSE transmission risk due to the abandonment of unstabled livestock carcasses in the countryside, this traditional practice in the Mediterranean region should be legalized in order to increase the availability, dispersion and quality of food for threatened scavengers. Once legalized, this practice should be prioritized over the spatially concentrated disposal of large amounts of carcasses from medicated stabled livestock to reduce the risk and effects of drug ingestion and acquisition and transmission of pathogens by vultures. [source] Role of mitogen-activated protein kinases, nuclear factor-,B, and interferon regulatory factor 3 in Toll-like receptor 4-mediated activation of HIV long terminal repeatAPMIS, Issue 2 2009RANDI S. BERG Monocytes/macrophages are known to represent a potential reservoir of human immunodeficiency virus type 1 (HIV-1), which ensures continuous replication of the virus in patients on highly active antiretroviral therapy (HAART). Infected macrophages are a highly productive source of HIV-1 during infections with common opportunistic pathogens. Previous studies report that toll like receptors (TLR)s play a role in HIV-1 replication in macrophages. Here, we investigate the three main pathways activated through TLR4 and the interactions with the HIV-1 long terminal repeat (LTR), using human embryonic kidney (HEK) 293 cells expressing TLR4 and transfected with a luciferase reporter under the control of the HIV-1 LTR. Here, we demonstrate, that TLR4-mediated activation of HIV-LTR is largely governed by the nuclear factor-,B pathway. Neither of the mitogen-activated protein kinases ERK1/2, JNK, or p38 nor the transcription factor interferon regulatory factor 3 were involved in the direct transactivation of HIV-LTR through stimulation of TLR4. [source] | ||||||||||||||||