An extensively-drug resistant (XDR) Escherichia coli W60 was isolated from the urine sample of a patient. The genetic basis for its XDR phenotype was investigated, particularly the basis for its resistance toward β-lactam/BLI (β-Lactamase Inhibitor) combinations. Following determination of the XDR phenotype, third generation genomic sequencing was performed to identify genetic structures in E. coli W60. Further cloning analysis was performed to identify determinants of β-lactam/BLI combination resistance. It was found that E. coli W60 is resistant to nearly all of the tested antibiotics including all commonly used β-lactam/BLI combinations. Analysis of the genomic structures in E. coli W60 showed two novel transferable plasmids are responsible for the resistance phenotypes. Further genetic analysis showed blaNDM–5 leads to high resistance to β-lactam/BLI combinations, which was enhanced by co-expressing bleMBL. pECW602 harbors a truncated blaTEM that is not functional due to the loss of the N-terminal signal peptide coding region. Research performed in this work leads to several significant conclusions: the XDR phenotype of E. coli W60 can be attributed to the presence of transferable multidrug resistance plasmids; NDM-5 confers high resistance to β-lactam/BLI combinations; co-expression of bleMBL enhances resistance caused by NDM-5; the signal peptides of TEM type β-lactamases are essential for their secretion and function. Findings of this work show the danger of transferable multidrug resistance plasmids and metallo-β-lactamases, both of which should be given more attention in the analysis and treatment of multidrug resistant pathogens.
We report for the first time, the use of pulsed laser annealing (PLA) on multiple-gate field-effect transistors (MuGFETs) with silicon-carbon (Si 1−x C x ) source and drain (S/D) for enhanced dopant activation and improved strain effects. Si 1−x C x S/D exposed to consecutive laser irradiations demonstrated superior dopant activation with a ∼60% reduction in resistivity compared to rapid thermal annealed S/D. In addition, with the application of PLA on epitaxially grown Si 0.99 C 0.01 , substitutional carbon concentration C sub increased from 1.0% (as grown) to 1.21%. This is also significantly higher than the C sub of 0.71% for rapid thermal annealed Si 0.99 C 0.01 S/D. With a higher strain and enhanced dopant activation, MuGFETs with laser annealed Si 0.99 C 0.01 S/D show a ∼53% drain-current improvement compared to MuGFETs with rapid thermal annealed Si 0.99 C 0.01 S/D.
We report the first demonstration of a novel germanium-enrichment process for forming a silicon-germanium (SiGe) source/drain (S/D) stressor with a high Ge content. The process involves laser-induced local melting and intermixing of a Ge layer with an underlying Si 0.8 Ge 0.2 S/D region, leading to a graded SiGe S/D stressor with a significant increase in the peak Ge content. Various laser fluences were investigated for the laser annealing process. The process is then successfully integrated in a device fabrication flow, forming strained silicon-on-insulator p-channel field-effect transistors (p-FETs) with a high Ge content in SiGe S/D. A drive current enhancement of ∼12% was achieved with this process, as compared to a strained p-FET with Si 0.8 Ge 0.2 S/D p-FETs. The I Dsat enhancement, primarily attributed to strain-induced mobility improvement, is found to increase with decreasing gate lengths.Index Terms-Germanium (Ge) enrichment, laser annealing (LA), strained transistor.
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