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Klebsiella pneumoniae is a Gram-negative bacterium associated with a wide range of community- and hospital-acquired infections. The emergence of clonal hypervirulent strains resistant to last-resort antimicrobial agents has become a global concern. The Kingdom of Saudi Arabia (KSA), with its diverse population and high tourism traffic, serves as a platform where the spread of multidrug-resistant (MDR) strains are facilitated. However, the knowledge of epidemiology and population diversity of MDR K. pneumoniae in KSA is scarce. We conducted a comprehensive genomic survey on 352 MDR K. pneumoniae isolates systematically collected from bloodstream and urinary tract infections in 34 hospitals across 15 major cities in KSA during 2022 and 2023. Whole-genome sequencing on the isolates was performed, followed by genomic epidemiology and phylodynamic analysis. Our study revealed a dynamic population characterized by the rapid expansion of several dominant clones, including, ST2096, ST147, and ST231, which were estimated to have emerged within the past decade. These clones exhibited widespread dissemination across hospitals and were genetically linked to global strains, particularly from the Middle East and South Asia. All major clones harboured plasmid-borne ESBLs and carbapenemase genes, with plasmidome analysis identifying multiple IncH, IncA/C and IncL plasmids underlying the MDR-hypervirulent phenotype. These plasmids were shared between major clones and became acquired on the same time scales as the expansion of the dominant clones. Our results report ST2096 as an emerging MDR-hypervirulent clone, emphasizing the need for monitoring of the circulating clones and their plasmid content in the KSA and broader West Asia.

To evaluate the potential role of in situ formed Sr-Ti-O species as a ferroelectric component able to enhance the photocatalytic properties of an adjacent TiO 2 semiconductor, Cu-doped/graphene oxide (GO)/TiO 2 nanotubes (TiNTs) composites (with 0.5 wt % Cu and 1.0 wt % GO) have been synthesized while progressive amounts of strontium (up to 1.0 wt %) were incorporated at the surface of the composite through incipient wetness impregnation followed by post-thermal treatment at 400 °C. The different resulting photocatalytic systems were then first deeply characterized by means of N 2 adsorption-desorption measurements, X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis DR), Raman and photoluminescence (PL) spectroscopies, and scanning electron microscopy (SEM) (with energy-dispersive X-ray (EDX) spectroscopy and Z -mapping). In a second step, optimization of the kinetic response of the Sr-containing composites was performed for the formic acid photodegradation under UV irradiation. The Sr-containing Cu/GO/TiNT composites were then fully characterized by electrochemical impedance spectroscopy (EIS) for their dielectric properties showing clearly the implication of polarization induced by the Sr addition onto the stabilization of photogenerated charges. Finally, a perfect correlation between the photocatalytic kinetic evaluation and dielectric properties undoubtedly emphasizes the role of ferroelectric polarization as a very valuable approach to enhance the photocatalytic properties in an adjacent semiconductor., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)