Multidrug-Resistant ESBL/AmpC-Producing Klebsiella pneumoniae Isolated from Healthy Thoroughbred Racehorses in Japan

Extended-spectrum β-lactamase (ESBL)- and AmpC β-lactamase (AmpC)-producing Klebsiella spp. have become a major health problem, leading to treatment failure in humans and animals. This study aimed to evaluate the presence of ESBL/AmpC-producing Klebsiella spp. isolated from racehorses in Japan. Feces samples from 212 healthy Thoroughbred racehorses were collected from the Japan Racing Association Training Centers between March 2017 and August 2018. ESBL/AmpC-producing Klebsiella spp. were isolated using selective medium containing 1 µg/mL cefotaxime. All isolates were subjected to bacterial species identification (MALDI-TOF MS), antimicrobial susceptibility test (disk diffusion test), characterization of resistance genes (PCR), conjugation assay, and genetic relatedness (multilocus sequence typing/MLST). Twelve ESBL/AmpC-producing Klebsiella pneumoniae (ESBL/AmpC-KP) were isolated from 3.3% of horse samples. Antimicrobial resistance profiling for 17 antimicrobials showed all ESBL/AmpC-KP were multidrug-resistant (MDR). Only 1 isolate was confirmed as an ESBL producer (blaCTX-M-2-positive), whereas the other 11 isolates were plasmid-mediated AmpC (pAmpC) producers (blaCMY positive). On the basis of MLST analysis, the ESBL-KP isolate was identified as sequence type (ST)-133 and four different STs among AmpC-KP isolates, ST-145, ST-4830, ST-4831, and ST-4832, were found to share six of the seven loci constituting a single-locus variant. This is the first study to show K. pneumoniae carrying MDR pAmpC isolated from a racehorse.Citation: Sukmawinata, E.; Uemura, R.; Sato, W.; Thu Htun, M.; Sueyoshi, M. Multidrug-Resistant ESBL/AmpC-Producing Klebsiella pneumoniae Isolated from Healthy Thoroughbred Racehorses in Japan. Animals 2020, 10, 369. https://doi.org/10.3390/ani1003036

A Computer Software Program using Models for Molecular Symmetry

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Precise Measurement of B Meson Lifetimes with Hadronic Decay Final States

journal articl

シモーヌ・シュヴァルツ＝バルト『奇跡のテリュメに雨と風』におけるシスターフッド

departmental bulletin pape

ギジュツ ベンチャー キギョウ ト ベンチャー キャピタル カツヨウ ホウ

video/mp4講演場所: 先端科学技術研究調査センター1階研修ホール講演者所属: フューチャーベンチャーキャピタル株式会社社長vide

Tellurium Goes for a Ride on the “Ferrous” Wheel: Interactions of Te(VI) and Te(IV) with Fe(II)-Bearing Minerals

Compared to more abundant metalloids (e.g., As, Se, and Sb), little is known regarding the biogeochemistry of tellurium (Te), a critical metal whose use in CdTe photovoltaic solar cells is driving increasing global demand for this element. To understand the redox behavior of Te under ferrugenic/sulfidogenic conditions, we examined the potential for reduction of Te(VI) and Te(IV) in aqueous suspensions containing Fe(II) as siderite, vivianite, green rust, magnetite, or mackinawite; Fe(II)-bearing minerals which are often formed during microbial reduction of Fe(III) oxides. In the mackinawite systems, complete reduction of Te(VI) or Te(IV) to Te(0) was observed within 12 h, and near complete reduction (>90% Te(0)) was observed within 2.5 days in the green rust systems. In the presence of siderite, complete reduction of Te(VI) or Te(IV) to Te(0) occurred within 60 days. We observed >60% reduction of Te(VI) to Te(IV) within 2.5 days in the magnetite system, but Te(0) did not form until 120 days; however, complete reduction to Te(0) was observed within 120 days when starting with Te(IV). With vivianite there was >80% reduction of Te(VI) to Te(IV) within 12 h, without further reduction to Te(0) over the duration of the experiment (120 days); in the Te(IV)-vivianite system, there was no evidence of Te(IV) reduction within 120 days. The reduction of Te(VI) and Te(IV) in soils and sediments has been largely attributed to direct reduction by microbes; however, the reduction of Te(VI) and Te(IV) by Fe(II)-bearing minerals suggests that abiotic or coupled biotic–abiotic processes may also play a critical role in Te redox chemistry in natural and engineered environments

XAFS Investigation of the Interactions of U^VI with Secondary Mineralization Products from the Bioreduction of Fe^III Oxides

Biogenic FeII phases (magnetite, green rust, siderite, vivianite, etc.) provide a reservoir of reducing capacity in many subsurface environments that may contribute to the reduction of contaminants such as UVI. We have examined the uptake and reduction of UVI in the presence of biogenic green rust (BioGR), magnetite (BioMAG), and siderite (BioSID) formed during the reduction of FeIII oxides by Shewanella putrefaciens CN32. Within 48 h, total solution-phase UVI concentrations decreased from 500 μM to 1.5 μM, 392 μM, and 472 μM in the U-BioGR, U-BioMAG, and U-BioSID systems, respectively. Analysis of the samples by U LIII extended X-ray absorption fine structure spectroscopy (EXAFS) indicated that despite a stoichiometric excess of FeII, no more than 6% of UVI was reduced to UIV in the U-BioSID system, and no more than 22% of UVI was reduced in the U-BioMAG system. For comparison, in the U-BioGR system, >99% of UVI was reduced to UIV. Uptake of UVI by BioGR and BioMAG was accompanied by formation of nanoparticulate uraninite. The U EXAFS data for the U-BioSID system were consistent with partial UVI/UIV substitution for FeII in the surface layer of siderite particles and adsorption of UIV

Effects of Ag^I, Au^III, and Cu^II on the Reductive Dechlorination of Carbon Tetrachloride by Green Rust

Green rusts (GRs), mixed iron(II)/iron(III) hydroxide minerals found in many suboxic environments, have been shown to reduce a range of organic and inorganic contaminants, including several chlorinated hydrocarbons. Many studies have demonstrated the catalytic activity of transition metal species in the reduction of chlorinated hydrocarbons, suggesting the potential for enhanced reduction by GR in the presence of an appropriate transition metal catalyst. Reductive dechlorination of carbon tetrachloride (CT) was examined in aqueous suspensions of GR amended with AgI, AuIII, or CuII. The CT reduction rates were greatly increased for systems amended with CuII, AuIII, and AgI (listed in order of increasing rates) relative to GR alone. Observed intermediates and products included chloroform, dichloromethane, chloromethane, methane, acetylene, ethene, ethane, carbon monoxide, tetrachloroethene, and various nonchlorinated C3 and C4 compounds. Product distributions for the reductive dechlorination of CT were highly dependent on the transition metal used. A reaction pathway scheme is proposed in which CT is reduced primarily to methane and other nonchlorinated end products, largely through a series of one-electron reductions forming radicals and carbenes/carbenoids. Recently, X-ray absorption fine structure analysis of aqueous GR suspensions amended with AgI, AuIII, or CuII showed that the metals were reduced to their zerovalent forms. A possible mechanism for CT reduction is the formation of a galvanic couple involving the zerovalent metal and GR, with reduction of CT occurring on the surface of the metal and GR serving as the bulk electron source. The enhanced reduction of CT by GR suspensions amended with AgI, AuIII, or CuII may prove useful in the development of improved materials for remediation of chlorinated organic contaminants

Binding of Hg^II to High-Affinity Sites on Bacteria Inhibits Reduction to Hg⁰ by Mixed Fe^II/III Phases

Magnetite and green rust have been shown to reduce aqueous HgII to Hg0. In this study, we tested the ability of magnetite and green rust to reduce HgII sorbed to 2 g·L–1 of biomass (Bacillus subtilis), at high (50 μM) and low (5 μM) Hg loadings and at pH 6.5 and 5.0. At high Hg:biomass loading, where HgII binding to biomass is predominantly through carboxyl functional groups, Hg LIII-edge X-ray absorption spectroscopy showed reduction of HgII to Hg0 by magnetite. Reduction occurred within 2 h and 2 d at pH 6.5 and 5.0, respectively. At low Hg:biomass loading, where HgII binds to biomass via sulfhydryl functional groups, HgII was not reduced by magnetite at pH 6.5 or 5.0 after 2 months of reaction. Green rust, which is generally a stronger reductant than magnetite, reduced about 20% of the total HgII bound to biomass via sulfhydryl groups to Hg0 in 2 d. These results suggest that HgII binding to carboxyl groups does not significantly inhibit the reduction of HgII by magnetite. However, the binding of HgII to biomass via sulfhydryl groups severely inhibits the ability of mixed FeII/III phases like magnetite and green rust to reduce HgII to Hg0. The mobility of heavy metal contaminants in aquatic and terrestrial environments is greatly influenced by their speciation, especially their oxidation state. In the case of Hg, reduction of HgII to Hg0 can increase Hg mobility because of the volatility of Hg0. Since Hg is typically present in aquatic and terrestrial systems at low concentrations, binding of HgII to high-affinity sites on bacteria could have important implications for the potential reduction of HgII to Hg0 and the overall mobility of Hg in biostimulated subsurface environments