Publications by authors named "Keiji Nakamura"
Background: Dexamethasone is currently administered for Coronavirus disease 2019(COVID-19); however, there are concerns about its effect on specific antibodies' production. The aim of this study was to evaluate whether specific antibodies were affected by COVID-19 severity and corticosteroid treatment.
Methods: Of 251 confirmed COVID-19 patients admitted to our hospital between January 26 and August 10, 2020, the early period of the pandemic, 75 patients with sera within 1 month of onset and 1 month or longer were included in the research.
Article Synopsis
- Shiga toxin-producing E. coli (STEC) causes severe gastrointestinal issues, particularly linked to Stx2, which poses greater risks than Stx1.
- A study of 71 strains in the O145:H28 lineage reveals the dynamic nature of Stx phages, including their acquisition, transfer, and variations affecting Stx2 production levels.
- Short-tailed Stx2 phages are associated with higher production levels of Stx2 than long-tailed variants, highlighting genetic differences that influence these levels.
Article Synopsis
- The study investigates the clinical outcomes and viral characteristics of immunocompromised patients with COVID-19 during the Omicron variant wave, comparing them to non-immunocompromised patients.
- Among 28 immunocompromised patients, half received monoclonal antibodies, and the severity of infections varied with 50% having mild/moderate disease and a low hospitalization mortality rate of 3.6%.
- The results showed slower viral clearance in immunocompromised patients compared to controls, but those who received monoclonal antibodies had improved viral clearance, highlighting the importance of these treatments in managing COVID-19 among immunocompromised individuals.
We reviewed bloodstream infections in the elderly in Japan, referring to data recently reported from the National Center for Global Health and Medicine in Tokyo. We divided the locations of bloodstream infections into Hospital-onset (HO), healthcare-associated (HCA), and CA (community-acquired), as the elderly reside in different places. The study focused on the fact that the general condition and underlying diseases of the elderly differ by age group.
View Article and Find Full Text PDFMicrobiota consisting of various fungi and bacteria have a significant impact on the physiological functions of the host. However, it is unclear which species are essential to this impact and how they affect the host. This study analyzed and isolated microbes from natural food sources of larvae, and investigated their functions.
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- Plasmids contribute significantly to the genetic diversity of bacteria, as evidenced by the study analyzing 142 closed genomes, which identified 132 plasmids in various strains, highlighting their role in genome evolution.
- The research found that while there was no significant difference in plasmid numbers between clinical and non-clinical strains, certain hospital-adapted lineages (like clade 2) contained more plasmids, with a notable proportion being associated with antimicrobial and heavy metal resistance.
- Clustering analysis revealed distinct groups of plasmids with varied GC content and highlighted their potential for interclade transmission and wider host-range capabilities, suggesting a complex ecological relationship among strains in different environments. *
Article Synopsis
- - The study investigates the virulence of various strains of Shigatoxigenic and enteropathogenic E. coli (STEC and EPEC) O80:H2 and other strains in moth larvae using a ColV conjugative plasmid model.
- - Results showed that STEC and EPEC O80:H2, as well as some O80:non-H2 strains, can be lethal to the larvae at high concentrations, primarily due to the Stx2d toxin and components of the pS88 plasmid.
- - While moth larvae serve as a useful initial model for studying bacterial pathogen virulence, they have limitations in identifying specific virulence factors of certain strains.
Article Synopsis
- This study investigates the prevalence and impact of bacteremia in older adults (ages 65+) to understand their unique susceptibility to infections and the factors influencing their mortality rates.
- A total of 1716 cases were analyzed, with different age groups (pre-old, old, and super-old) showing distinct patterns of infections and varying 7-day mortality rates (7.4%, 5.8%, and 14.2%, respectively).
- Key findings indicate that super-old age and hospital-onset bacteremia significantly increase the risk of death, while consulting infectious disease specialists can help reduce mortality rates among these patients.
Article Synopsis
- - The study focuses on cryptic clade I (C-I) within the Escherichia genus, suggesting it's a subspecies of E. coli that is challenging to differentiate from the classic E. coli, leaving its population structure and virulence unclear.
- - Researchers analyzed 804 isolates, identifying 465 true C-I strains, including a harmful strain linked to a patient with bloody diarrhea, finding a significant presence of virulence and antibiotic resistance genes in these strains.
- - The results indicate that C-I strains could be emerging human pathogens, mainly sourced from bovines, highlighting the need for more extensive surveillance and studies to understand C-I strains and their impact on health better.
Article Synopsis
- Pathogenic strains in swine lead to significant economic losses, particularly in Japan where antimicrobial use is higher compared to other farm animals.
- A recent study analyzed 1,708 strains from diseased swine over nearly three decades (1991-2019) and identified increasing multidrug-resistant strains, including resistant serogroups O116 and OSB9.
- The study found that although third-generation cephalosporins had a low resistance rate, alternative antimicrobials like apramycin and bicozamycin were more effective against highly multidrug-resistant strains.
Article Synopsis
- "Candidatus Rickettsia kotlanii" is a newly identified tick-borne pathogen associated with spotted fever, first found in Hungary in 2006.
- Researchers sequenced the complete genomes of two Japanese isolates to clarify its evolutionary relationship within the spotted fever group of Rickettsia, revealing that it forms an independent branch within this category.
- Despite having nearly identical genomes, the isolates came from different tick species and locations, indicating low genetic diversity, while some genes present in "Ca. R. kotlanii" were found to be degraded, necessitating further study on its unique features.
Article Synopsis
- Shiga toxin (Stx), produced by Stx-producing E. coli (STEC), is crucial for the bacteria's virulence and is encoded by bacteriophages known as Stx phages.
- A study focusing on the O26:H11 STEC lineage (specifically ST21) revealed significant genetic diversity among Stx1a phages, indicating various evolutionary changes, including the replacement of phages.
- Additionally, the research showed notable differences in Stx1 toxin production linked to variations in Stx1 phages and host factors, emphasizing the complexity of phage-host interactions in toxin production.
Article Synopsis
- The study focuses on Shiga toxin-producing E. coli (STEC), particularly on the O165:H25 strain and its relationship to closely related strains, defining them all as clonal complex 119 (CC119).
- Researchers conducted whole-genome sequencing of 202 strains to analyze their genetic similarities and differences, focusing on the presence and behavior of specific phages and virulence genes.
- The findings revealed that the CC119 lineage retains certain genetic traits that enhance virulence, but also shows notable variations in toxin production and lacks genes typical for tellurite resistance, indicating potential vulnerabilities in these strains.
The origin of human and calf infections by Shigatoxigenic (STEC) and enteropathogenic (EPEC) O80:H2 is still unknown. The aim of this study was to identify O80 in healthy cattle with an emphasis on melibiose non-fermenting O80:H2. Faecal materials collected from 149 bulls at 1 slaughterhouse and 194 cows on 9 farms were tested with O80 antigen-encoding gene PCR after overnight growth in enrichment broths.
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- * The study involved genome sequencing of 510 strains, including 147 from Japan, and analyzed variations in Stx2 production levels, which are associated with disease severity.
- * Results showed distinct genetic diversity in Stx2a phages among the lineages, particularly that SG8_30 strains produced more Stx2 and caused more severe illnesses compared to SG8_32 strains.
Article Synopsis
- Lactose utilization in Escherichia coli is generally detected on lactose-containing media, but some Shiga toxin-producing strains (O121:H19) exhibit a delayed lactose utilization (DLU) phenotype, requiring 48 hours for detection instead of the usual 24 hours.
- The DLU phenotype is linked to an insertion sequence (IS) disrupting the lactose utilization gene, and its effects can only be observed after exposure to lactose.
- Research revealed that the IS can be excised, allowing the reactivation of the lactose utilization gene, and showed that most circulating O121:H19 strains harbor this IS insertion, explaining the prevalence of the DLU phenotype.
Background: Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction, including dysregulation of the hypothalamic-pituitary-adrenal axis with salivary cortisol changes. However, the role of gastrointestinal microbiota during IBS symptom exacerbation remains unclear. We tested the hypothesis that the microbial species, gene transcripts, and chemical composition of fecal and oral samples are altered during the exacerbation of IBS symptoms.
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- The XN-31 prototype (XN-31p) is a new automated device that quickly measures malaria-infected red blood cells (MI-RBC) and identifies malaria parasite species in about one minute using flow cytometry.
- Clinical tests were conducted with 80 patients in Japan, comparing the XN-31p results to standard methods like microscopy, rapid diagnostic tests, and nested PCR.
- The XN-31p showed high accuracy, detecting 32 malaria-positive cases that closely matched microscopic observations, and demonstrated a strong correlation in the ratio of infected red blood cells with traditional methods.
A 53-year-old male Japanese patient with COVID-19 was admitted to our hospital after his respiratory condition worsened on day 9 of the disease. With the diagnosis of severe COVID-19, treatment with remdesivir, dexamethasone, and unfractionated heparin was started for the prevention of thrombosis. Although the patient's respiratory status data improved after treatment, severe respiratory failure persisted.
View Article and Find Full Text PDFis an enterohepatic that causes bacteremia and other diseases in humans. While -like strains are isolated from animals, including dog isolates belonging to a recently proposed , little is known about the genetic differences between and these animal isolates. Here, we sequenced 43 or -like strains isolated from humans, hamsters, rats and dogs and collected 81 genome sequences of , and other enterohepatic strains from public databases.
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- The text discusses a significant nosocomial pathogen responsible for opportunistic infections and emphasizes the threat posed by emerging multidrug-resistant (MDR) strains to global health.
- A large-scale genome analysis of this pathogen and its closely related species was conducted, identifying 14 distinct clades based on genomic characteristics.
- Clades 1 and 2 contained most hospital-related isolates with high antimicrobial resistance, suggesting they are adapted to clinical environments, while new genomic insights may lead to a reevaluation of the pathogen's classification and understanding of its evolution.
Article Synopsis
- Old age significantly increases the risk of severe COVID-19, and this study aimed to explore the clinical and epidemiological characteristics of hospitalized elderly patients across different age groups.
- A retrospective analysis of 4,701 patients revealed that most had comorbidities, with hypertension being common, while the prevalence of dementia and other serious conditions increased with age.
- The study found that while the death rate rose with age, factors like male sex and specific health conditions distinguished the risk levels for severe COVID-19 differently among the younger elderly (65-74) and older age groups (75-89 and 90+).
Article Synopsis
- Shiga toxin (Stx)-producing Escherichia coli (STEC), particularly O121:H19, are emerging foodborne pathogens linked to serious illnesses like hemorrhagic colitis and hemolytic uremic syndrome.
- A global whole genome sequencing analysis of 638 O121:H19 strains revealed four distinct lineages, with significant differences in their virulence factors and prophage characteristics between the major lineages L1 and L3.
- The study highlights that strains in lineage L1 produce much higher levels of Stx2a toxin due to their highly conserved short-tailed phage genomes, while lineage L3 shows notable genetic diversity with long-tailed phages.
Article Synopsis
- Remdesivir is an antiviral drug that improves clinical outcomes in COVID-19 patients after five days of treatment and can accelerate recovery by 31%.
- A case study of a 63-year-old man with severe COVID-19 on ECMO revealed a specific treatment regimen with remdesivir over ten days, including a loading dose and daily maintenance doses.
- The pharmacokinetic analysis found normal serum creatinine levels and measured remdesivir and its metabolite GS-441524 at different times post-administration, indicating that monitoring these plasma concentrations is important for patients on ECMO.