Publications by authors named "Chika Arai"

Objectives: The suppression of antimicrobial-resistant bacteria (ARB) is an important issue worldwide. In recent years, the presence of various ARB in the oral cavity has been reported, but the details remain unclear. Therefore, we aimed to isolate ARB from the oral cavity and investigate the factors affecting ARB colonization.

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Background: Quality control (QC) of carbapenem susceptibility testing for Gram-negative bacteria faces challenges due to limited measuring ranges and the lack of suitable QC strains. This study aimed to select and evaluate QC strains for meropenem antimicrobial susceptibility testing (AST) through a pilot external quality assessment (EQA).

Methods: Candidate QC strains for meropenem AST were selected based on primary AST data and genomic information from the Japan Antimicrobial Resistant Bacterial Bank.

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Unlabelled: The emergence of drug-resistant bacteria, particularly methicillin-resistant (MRSA) and vancomycin-resistant enterococci (VRE), has increased the need to discover novel antimicrobial agents that are effective against these species. Here, we describe the identification and purification of the mutacin BHT-B-like gene locus and bacteriocin peptide from , which is closely related to ; hence, we named this bacteriocin ursoricin. Ursoricin is a cationic, chromosome-encoded peptide that has potent antimicrobial effects against Gram-positive pathogens, including MRSA and VRE, with minimum inhibitory concentrations in the micromolar range.

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Article Synopsis
  • Atopic dermatitis (AD) frequently recurs and is primarily associated with the presence of Staphylococcus aureus, particularly strain ST188, which correlates strongly with increased disease activity.
  • Comprehensive genomic analysis of 261 S. aureus isolates from both AD patients and healthy individuals revealed distinct variations between skin conditions, highlighting the dominance of certain strains in AD lesions.
  • Notably, ST188 and ST97 strains displayed unique genetic features that may enhance survival in the low tryptophan environment of AD skin, while exhibiting a lack of enterotoxin genes compared to strains found in Europe and North America.
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  • A study found third-generation-cephalosporin-resistant Gram-negative bacteria in the mouths of residents in a long-term care facility, prompting an investigation into how these bacteria respond to various disinfectants.
  • Researchers tested the susceptibility of these bacteria, including Pseudomonas and Acinetobacter, to several disinfectants like povidone-iodine and chlorhexidine, comparing results from oral and rectal isolates.
  • The results showed that oral antibiotic-resistant bacteria also have disinfectant resistance, particularly Pseudomonas aeruginosa, indicating a growing concern about the prevalence of resistant bacteria in healthcare settings.
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  • * Out of 178 residents studied, 146 were analyzed for ARB, with significant findings including 42.7% carrying ESBL-producing Enterobacterales and a notable association between Pseudomonas aeruginosa and increased mortality among residents.
  • * This research highlights the correlation between ARB colonization and enteral nutrition, establishing the urgency to recognize ARB prevalence in LTCFs as a critical factor affecting resident health.
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The benzo[a]phenoxazine derivative, SSJ-183 has shown excellent anti-malarial efficacy and safety. However, its mechanism of action is unclear. We investigated the effect of SSJ-183 on the rodent malarial parasite, Plasmodium berghei.

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SSJ-127, a novel antimalarial rhodacyanine derivative, has shown potent antimalarial activity against chloroquine-resistant Plasmodium strains in vitro and subcutaneous administration of SSJ-127 results in a complete cure of a mouse malaria model. SSJ-127 was detected by fluorescence microscopy in the mouse malaria parasites Plasmodium berghei after exposure of infected red blood cells to the compound in vitro and in vivo. Selective accumulation of SSJ-127 in an organelle is observed in all blood stages of live malaria parasites.

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Malaria is a serious infectious disease caused by protozoan parasites in tropical and subtropical regions. Even inhabitants of temperate zones are exposed to the danger of malaria infection because of travel and global warming. Novel, effective, safe, and inexpensive drugs are required to treat malaria and contribute to the global goal of eradication.

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Anti-Leishmania in vitro and in vivo activities of various rhodacyanine derivatives have been examined. Among them, the fluorinatied variant SJL-01 (8) showed IC(50) of 0.011 microM against Leishmania donovani strain MHOM/ET/67/L82 (selective index of >15000) and 95-97% inhibition against L.

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In vivo antimalarial drug candidates screening test was carried out on a series of water-soluble 3,7-bis(dialkylamino)phenoxazin-5-ium derivatives. Among them, 3-(diethylamino)-7-(piperidin-1-yl)phenoxazin-5-ium chloride (SSJ-206) showing highest efficacy was chosen for further pharmcodynamics and pharmacokinetics study. It was supported from these data that the phenoxazinium salts, SSJ-206, would be one of hopeful candidates as an oral antimalarial drug.

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3,7-Bis(dialkylamino)phenoxazinium salts were synthesized and evaluated for in vitro activities against Plasmodium falciparum, Trypanosoma cruzi, T. brucei rhodesiense, and Leishmania donovani. Notably, the compounds showed potent antiprotozoal activities, especially against P.

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