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Human Pathogenic Bacteria (human + pathogenic_bacteria)
Selected AbstractsThe 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] Status of Streptomycin Resistance Development in Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola in China and their Resistance CharactersJOURNAL OF PHYTOPATHOLOGY, Issue 9 2010Ying Xu Abstract Rice leaves with bacterial blight or bacterial leaf streak symptoms were collected in southern China in 2007 and 2008. Five hundred and thirty-four single-colony isolates of Xanthomonas oryzae pv. oryzae and 827 single-colony isolates of Xanthomonas oryzae pv. oryzicola were obtained and tested on plates for sensitivity to streptomycin. Four strains (0.75%) of X. oryzae pv. oryzae isolated from the same county of Province Yunnan were resistant to streptomycin, and the resistance factor (the ratio of the mean median effective concentration inhibiting growth of resistant isolates to that of sensitive isolates) was approximately 226. The resistant isolate also showed streptomycin resistance in vivo. In addition to resistant isolates, isolates of less sensitivity were also present in the population of X. oryzae pv. oryzae from Province Yunnan. However, no isolates with decreased streptomycin-sensitivity were obtained from the population of X. oryzae pv. oryzicola. Mutations in the rpsL (encoding S12 protein) and rrs genes (encoding 16S rRNA) and the presence of the strA gene accounting for streptomycin resistance in other phytopathogens or animal and human pathogenic bacteria were examined on sensitive and resistant strains of X. oryzae pv. oryzae by polymerase chain reaction amplification and sequencing. Neither the presence of the strA gene nor mutations in the rpsL or rrs were found, suggesting that different resistance mechanisms are involved in the resistant isolates of X. oryzae pv. oryzae. [source] Broad-spectrum protein biosensors for class-specific detection of antibioticsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2005Cornelia C. Weber Abstract The dramatically increasing prevalence of multi-drug-resistant human pathogenic bacteria and related mortality requires two key actions: (i) decisive initiatives for the detection of novel antibiotics and (ii) a global ban for use of antibiotics as growth promotants in stock farming. Both key actions entail technology for precise, high-sensitive detection of antibiotic substances either to detect and validate novel anti-infective structures or to enforce the non-use of clinically relevant antibiotics. We have engineered prokaryotic antibiotic response regulators into a molecular biosensor configuration able to detect tetracycline, streptogramin, and macrolide antibiotics in spiked liquids including milk and serum at ng/mL concentrations and up to 2 orders of magnitude below current Swiss and EC threshold values. This broad-spectrum, class-specific, biosensor-based assay has been optimized for use in a storable ready-to-use and high-throughput-compatible ELISA-type format. At the center of the assay is an antibiotic sensor protein whose interaction with specific DNA fragments is responsive to a particular class of antibiotics. Binding of biosensor protein to the cognate DNA chemically linked to a solid surface is converted into an immuno-based colorimetric readout correlating with specific antibiotics concentrations. © 2004 Wiley Periodicals, Inc. [source] High-resolution structure of the antibiotic resistance protein NimA from Deinococcus radioduransACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2008Hanna-Kirsti S. Leiros Many anaerobic human pathogenic bacteria are treated using 5-nitroimidazole-based (5-Ni) antibiotics, a class of inactive prodrugs that contain a nitro group. The nitro group must be activated in an anaerobic one-electron reduction and is therefore dependent on the redox system in the target cells. Antibiotic resistance towards 5-Ni drugs is found to be related to the nim genes (nimA, nimB, nimC, nimD, nimE and nimF), which are proposed to encode a reductase that is responsible for converting the nitro group of the antibiotic into a nonbactericidal amine. A mechanism for the Nim enzyme has been proposed in which two-electron reduction of the nitro group leads to the generation of nontoxic derivatives and confers resistance against these antibiotics. The cofactor was found to be important in the mechanism and was found to be covalently linked to the reactive His71. In this paper, the 1.2,Å atomic resolution crystal structure of the 5-nitroimidazole antibiotic resistance protein NimA from Deinococcus radiodurans (DrNimA) is presented. A planar cofactor is clearly visible and well defined in the electron-density map adjacent to His71, the identification of the cofactor and its properties are discussed. [source] | ||||||||||