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isolation and in vitro susceptibility of acanthamoeba from a patient with keratitis.the acanthamoebae are facultative parasites of man, and may infect the brain, skin, bone, respiratory passages and eyes. over the past several years, acanthamoeba keratitis has become a growing problem. this is the first case isolating acanthamoeba polyphaga from a corneal biopsy of an ophthalmic patient in taiwan. direct impression smear by trichrome stain gave positive result. to provide effective clinical treatment, chemotherapeutic agents available for ophthalmic use were tested for its susc ...19892791723
identification of a general secretory pathway in a human isolate of burkholderia vietnamiensis (formerly b. cepacia complex genomovar v) that is required for the secretion of hemolysin and phospholipase c activities.members of the burkholderia cepacia complex can secrete proteases, lipases, and hemolysins. we report in this study the identification of a general secretory pathway present in a b. vietnamiensis (formerly genomovar v) clinical isolate, which is required for the efficient secretion of phospholipase c and hemolysin activities. southern blot hybridization experiments revealed that this general secretion pathway is highly conserved among the different genomovars of the b. cepacia complex and is hom ...200212071681
antibiotic susceptibilities of parachlamydia acanthamoeba in amoebae.parachlamydia acanthamoeba are intracellular bacteria of amoebae and are considered potential etiological agents of human pneumonia. we have determined the in vitro antibiotic susceptibilities of two strains (strain bn(9) and hall's coccus) in acanthamoeba polyphaga. the two strains were susceptible to tetracyclines, macrolides, and rifampin, but resistant to fluoroquinolones.200212183273
replication and long-term persistence of bovine and human strains of mycobacterium avium subsp. paratuberculosis within acanthamoeba polyphaga.free-living protists are ubiquitous in the environment and form a potential reservoir for the persistence of animal and human pathogens. mycobacterium avium subsp. paratuberculosis is the cause of johne's disease, a systemic infection accompanied by chronic inflammation of the intestine that affects many animals, including primates. most humans with crohn's disease are infected with this chronic enteric pathogen. subclinical infection with m. avium subsp. paratuberculosis is widespread in domest ...200616391127
elastase secretion in acanthamoeba polyphaga.acanthamoeba species are frequently isolated from soil and water collections. in the environment, the organisms multiply as phagotrophic trophozoites and encyst under adverse conditions. several species are known to infect man, causing keratitis and opportunistic diseases. the mechanisms underlying tissue damage and invasion by the amoebae are being elucidated and the involvement of secreted peptidases, particularly serine peptidases, has been demonstrated. here, elastase activity was examined i ...200919632188
viability of listeria monocytogenes in co-culture with acanthamoeba spp.listeria monocytogenes is a human pathogen, ubiquitous in the environment, and can grow and survive under a wide range of environmental conditions. it contaminates foods via raw materials or food-processing environments. however, the current knowledge of its ecology and, in particular, the mode of environmental survival and transmission of this intracellular pathogen remains limited. research has shown that several intracellular pathogens are able to survive or replicate within free-living amoeb ...200919645820
a dot/icm-translocated ankyrin protein of legionella pneumophila is required for intracellular proliferation within human macrophages and protozoa.the dot/icm type iv secretion system of legionella pneumophila translocates numerous bacterial effectors into the host cell and is essential for bacterial proliferation within macrophages and protozoa. we have recently shown that l. pneumophila strain aa100/130b harbours 11 genes encoding eukaryotic-like ankyrin (ank) proteins, a family of proteins involved in various essential eukaryotic cellular processes. in contrast to most dot/icm-exported substrates, which have little or no detectable role ...200818811729
are clinical isolates of pseudomonas aeruginosa more virulent than hospital environmental isolates in amebal co-culture test?pseudomonas aeruginosa is an important opportunistic pathogen in hospital-acquired infections. as an environmental bacterium, it colonizes soil and water as well as hospital water supply and shares its natural habitat with free-living amebae. it has been shown previously that an ameba host system can be used to analyze the virulence of p. aeruginosa strains. in this study we have developed a simple amebal co-culture test with acanthamoeba polyphaga to compare the virulence of p. aeruginosa betwe ...200616505663
characterization of legionella pneumophila pmia, a gene essential for infectivity of protozoa and macrophages.the ability of legionella pneumophila to cause pneumonia is dependent on intracellular replication within alveolar macrophages. the icm/dot secretion apparatus is essential for the ability of l. pneumophila to evade endocytic fusion, to remodel the phagosome by the endoplasmic reticulum (er), and to replicate intracellularly. protozoan and macrophage infectivity (pmi) mutants of l. pneumophila, which include 11 dot/icm mutants, exhibit defects in intracellular growth and replication within both ...200516177298
expression of multiple pili by legionella pneumophila: identification and characterization of a type iv pilin gene and its role in adherence to mammalian and protozoan cells.legionella pneumophila expresses pili of variable lengths, either long (0.8 to 1.5 microm) or short (0.1 to 0.6 microm), that can be observed by transmission electron microscopy. we have identified a gene in l. pneumophila with homology to the type iv pilin genes (pilel). an insertion mutation was constructed in pilel and introduced into the l. pneumophila wild-type strain by allelic exchange. the pilin mutant is defective for expression of long pili. reintroduction of the pilin locus on a cosmi ...19989529112
adherence of cysts and trophozoites of acanthamoeba to unworn rigid gas permeable and soft contact lenses.contact lens related acanthamoeba keratitis has been more often associated with the use of soft contact lenses than with the use of rigid gas permeable (rgp) contact lenses. we studied the adherence of acanthamoeba cysts and trophozoites to unworn rgp (silicone acrylate and fluoropolymer) and low and high water content soft contact lenses marketed in india. a human corneal isolate of acanthamoeba polyphaga suspended in saline (1 x 10(5) amoebae/ml) was used. lens segments were exposed to a. poly ...19958565194
survey of pathogenic free-living amoebae and legionella spp. in mud spring recreation area.acanthamoeba, hartmannella, and naegleria are free-living amoebae, ubiquitous in aquatic environments. several species within these genera are recognized as potential human pathogens. these free-living amoebae may facilitate the proliferation of their parasitical bacteria, such as legionella. in this study, we identified acanthamoeba, hartmannella, naegleria, and legionella using various analytical procedures and investigated their occurrence at a mud spring recreation area in taiwan. we investi ...200919457534
isolation and identification of amoeba-resisting bacteria from water in human environment by using an acanthamoeba polyphaga co-culture procedure.amoeba-resisting bacteria (arb) such as legionella spp. are currently regarded as potential human pathogens living in the environment. to detect arb from both human and environmental samples, co-culture with amoebae has been demonstrated as an efficient tool. however, using this procedure, mostly water from cooling towers and hospital water supplies have been investigated as the possible reservoir of arb. in the present study, we studied arb population in 77 environmental water samples including ...200818279351
biological characterization of a clinical and an environmental isolate of acanthamoeba polyphaga: analysis of relevant parameters to decode pathogenicity.acanthamoeba spp. consists of free-living amoebae, widespread in nature, which occasionally can cause human infections including granulomatous amoebic encephalitis and amoebic keratitis. acanthamoeba pathogenesis is not entirely known and correlations between pathogenic potential and taxonomy are complex issues. in order to decipher the definition of a pathogenic amoeba, the objective of this work was to decipher the definition of pathogenic amoeba by characterizing two isolates of acanthamoeba ...200717569030
role for the ankyrin eukaryotic-like genes of legionella pneumophila in parasitism of protozoan hosts and human macrophages.legionella pneumophila is a ubiquitous organism in the aquatic environment where it is capable of invasion and intracellular proliferation within various protozoan species and is also capable of causing pneumonia in humans. in silico analysis showed that the three sequenced l. pneumophila genomes each contained a common multigene family of 11 ankyrin (ank) genes encoding proteins with approximately 30-35 amino acid tandem ankyrin repeats that are involved in protein-protein interactions in eukar ...200818279343
acanthamoeba binds to extracellular matrix proteins in vitro.to identify host-tissue amoeba interactions that may be important in the pathogenesis of acanthamoeba keratitis, the ability of the opportunistic pathogen acanthamoeba polyphaga to bind various components of the extracellular matrix (collagen type iv, laminin, or fibronectin) was examined in vitro.19938449684
the interaction between acanthamoeba polyphaga and human osteoblastic cells in vitro.acanthamoeba spp. contains a group of free-living amoebae widespread in nature. these microorganisms may cause several diseases in humans including osteomyelitis. here we characterize the cellular interaction between clinical and freshwater isolates of a. polyphaga with human osteoblasts. amoeba cytoadherence was evaluated quantitatively and qualitatively. we observed that the clinical isolate readily adheres to human osteoblastic cells (hob) in a saturable and time-dependent fashion. the cytoad ...200616325369
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