OqxAB, a quinolone and olaquindox efflux pump, is widely distributed among multidrug-resistant Klebsiella pneumoniae isolates of human origin

Use of antibiotics among livestock contributes to the selection and dissemination of multidrug resistant (MDR) bacteria. Olaquindox and carbadox are quinoxaline derivatives with antibacterial properties that prevent dysentery and enhance weight gain in suckling pigs. Resistance to quinoxalines is mediated by the efflux pump OqxAB, which also extrudes antibiotics such as chloramphenicol and fluoroquinolones. The gene encoding this efflux pump, oqxAB, was initially detected within plasmid pOLA52, which was found in Escherichia coli isolated from swine manure. Dissemination of oqxAB has been noted in Salmonella species, and the original genetic reservoir of oqxAB was traced to the chromosome of Klebsiella pneumoniae. Surprisingly, OqxAB has been reported only in clinical isolates of K. pneumoniae from China, South Korea, and Spain

Plasmonic stimulated photocatalytic/electrochemical hydrogen evolution from water by (001) faceted and bimetallic loaded titania nanosheets under sunlight irradiation

This study demonstrates the synthesis of TiO2 nanosheets (TNST) exhibiting high percentage (54%) of exposed (001) facets and decorated with co-deposited gold and platinum nanoparticles (NPs). The as synthesized as well as modified sheets are then investigated for the photo-reduction of water under sunlight irradiation using different alcohols as hole-scavengers. Structural and morphological studies manifest the formation of well-defined sheet structure of TiO2 with average dimensions of 55 nm × 46 nm. The measured d spacing of 0.34 nm and 0.23 nm corresponds to (101) and (001) facets of anatase TiO2. The presence of Au and Pt was confirmed by electron diffraction and X-ray photoelectron spectroscopy. TiO2 nanosheets (TNST's) with 0.4 and 0.75 wt % of Au and Pt (Au0.4/Pt0.75-TNSTs), respectively were found to exhibit higher efficiency. Furthermore, photo-electrochemical (PEC) water splitting studies revealed the increase in photocurrent from 2 mA at 0.5 V to 4.5 mA at 0.65 V for Au0.4/Pt0.75-TNST photoelectrodes, which otherwise was 0.15 mA for the bare TNST photoelectrodes at the same potential. The observed PEC performance was well supported by impedance analysis, wherein Au0.4/Pt0.75-TNSTs (338 Ω) are found to exhibit lower resistance in comparison to bare TNST (737 Ω), which could be due to brilliant photo conductance and interfacial charge transfer properties of Au0.4/Pt0.75-TNSTs. Photocatalytically the Au0.4/Pt0.75-TNST produced ∼143 μmol h1 of H2 gas under direct sunlight irradiation, which is found equivalent to 16.1% apparent quantum efficiency