Beneficial Chromosomal Integration of the Genes for CTX-M Extended-Spectrum β-Lactamase in Klebsiella pneumoniae for Stable Propagation

Dominant F-type plasmids harboring the gene have been pointed out to be responsible for the dissemination of the CTX-M extended-spectrum-β-lactamase (ESBL)-producing K. pneumoniae. Recently, the emergence of K. pneumoniae isolates with the bla CTX-M gene in their chromosomes has been reported occasionally worldwide. Such a chromosomal location of the resistance gene could be beneficial for stable propagation, as was the Acinetobacter baumannii ST191 harboring chromosomal bla OXA-23 that is endemic to South Korea. Through the present study, particular clones were identified as having built-in resistance genes in their chromosomes, and the chromosomal integration events were tracked by assessing their genomes. The cefotaxime-resistant K. pneumoniae clones of this study were particularized as results of the fastidiousness for plasmids to acquire the bla CTX-M gene for securing the diversity and of the chromosomal addiction of the bla CTX-M gene for ensuring propagation.

Photonic droplets in a medium of carbon nanotubes

The numerical research of the photonic droplets dynamic in a carbon nanotube medium has been carried out. A stable propagation of these pulses has been detected at times down to tens of picoseconds. The propagation features of pulses at various parameters (velocity and pulse amplitude) have been shown as well.

Трехмерные предельно короткие оптические импульсы Эйри в фотонном кристалле с углеродными нанотрубками

The problem of the propagation dynamics of three-dimensional optical Airy pulses (light bullets) in a photonic crystal with carbon nanotubes is considered. It is numerically shown that the expected type of pulse exhibits a steady and stable propagation.