Ikuro Kasuga

Tigecycline is a last-resort antimicrobial against carbapenemase-producing <i>Enterobacterales</i> (CPE). However, mobile tigecycline resistance genes, <i>tet</i>(X) and <i>tmexCD-toprJ</i>, have emerged in China and have spread possibly worldwide. Tet(X) family proteins function as tigecycline-inactivating enzymes, and TMexCD-TOprJ complexes function as efflux pumps for tigecycline. Here, to the best of our knowledge we report a CPE isolate harboring both emerging tigecycline resistance factors

The influence of backwashing on the biofilm community developed on biological activated carbon (BAC) used in a drinking water treatment plant was investigated by means of bacterial cell enumeration and terminal-restriction fragment length polymorphism (T-RFLP) fingerprinting analysis of bacterial and eukaryotic ribosomal RNA genes (rDNA). After backwashing, the attached bacterial abundance in the top layer of the BAC bed decreased to 64% of that before backwashing. The community level changes ca

Antimicrobial resistance (AMR) is a serious public health concern. Many countries have implemented AMR surveillance programs for humans and animals, but a scheme for monitoring AMR in the environment has not yet been established. Class 1 integrons, which can acquire antimicrobial resistance genes (ARGs) to gene cassettes, were proposed as a candidate to evaluate the anthropogenic impacts on AMR. However, the association between class 1 integrons and ARGs in aquatic environments is less studied a

Catechol 2,3-dioxygenase (C23O) is an extradiol dioxygenase that plays an important role in degrading aromatic compounds such as those found at polluted sites. However, little is known about the diversity of C23O genes in unpolluted environments. In such environments, various factors, including the quality and quantity of dissolved organic matter (DOM), could influence the composition and behaviour of bacterial community possessing C230 genes. We investigated C23O genes in bacteria responding to

Nitrification is a key function of biological activated carbon (BAC) filters for drinking water treatment. It is empirically known that the nitrification activity of BAC filters depends on water temperature, potentially resulting in the leakage of ammonium from BAC filters when the water temperature decreases. However, the ammonium removal capacity of BAC filters and factors governing the capacity remain unknown. This study employed a bench-scale column assay to determine the volumetric ammonium

Colistin is one of the antibiotics of last resort for human health. However, the dissemination of the plasmid-mediated colistin resistance gene mcr-1 is of great concern globally. In the One Health framework, the environment is an important component for managing antimicrobial resistance. However, little information is available concerning the prevalence of mcr-1 in water environments. We aimed to reveal the prevalence of mcr-1 in different water environments in Hanoi, Vietnam. Quantitative PCR

The effects of different placements of rapid sand filtration on nitrification performance of BAC treatment in a pilot-scale plant were evaluated. In this plant, rapid sand filtration was placed after ozonation-BAC treatment in Process (A), while it preceded ozonation-BAC treatment in Process (B). Analysis of amoA genes of ammonia-oxidizing archaea (AOA) and bacteria (AOB) combined with nitrification potential test was conducted. BAC from Process (A) demonstrated slightly higher nitrification pot