担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： https://doi.org/10.1038/s41467-021-22317-7

Open Access

記述言語：英語   出版者・発行元：Journal of Infection and Chemotherapy  

Several studies have reported clinical isolates of Streptococcus mitis, Streptococcus oralis, and their related species (S. mitis/oralis group) with reduced carbapenem susceptibility. However, to date, no simple and accurate methods of detecting S. mitis/oralis group isolates with reduced carbapenem susceptibility have been reported. The meropenem ETEST misinterpreted 3 of 25 (12 %) meropenem-non-susceptible S. mitis/oralis group isolates as susceptible to meropenem. Therefore, we screened 38 disks containing 38 different β-lactams to detect S. mitis/oralis group strains with reduced carbapenem susceptibility using the disk-diffusion method. Additionally, using the agar dilution method to determine susceptibility, we identified the optimal antibiotic concentrations in agar medium to enable selective culture of meropenem-non-susceptible S. mitis/oralis group by culturing 25 meropenem-non-susceptible (meropenem minimum inhibitory concentration [MIC] >0.5 μg/mL) and 24 meropenem-susceptible (meropenem MIC ≤0.5 μg/mL) S. mitis/oralis group isolates on agar containing different concentrations of six β-lactams. Meropenem-susceptible and non-susceptible S. mitis/oralis group isolates were successfully differentiated using oxacillin- and cefoxitin-containing disks. Moreover, cefdinir-, flomoxef-, meropenem-, and doripenem-containing disks showed clear differences in the growth inhibitory zone diameter between the meropenem-susceptible and meropenem-non-susceptible S. mitis/oralis group isolates. Media containing 2 μg/mL oxacillin, 4–16 μg/mL cefoxitin, 2 μg/mL cefdinir, 2–4 μg/mL flomoxef, 0.06–0.25 μg/mL meropenem, and 0.06–0.12 μg/mL doripenem allowed selective culture of meropenem-non-susceptible S. mitis/oralis group strains. The disk-diffusion method using six β-lactam-containing disks and selective culture agar medium are the first-reported simple and accurate methods of detecting meropenem-non-susceptible S. mitis/oralis group suitable for use in clinical microbiology laboratories.

DOI： 10.1016/j.jiac.2025.102846

Web of Science

Scopus

PubMed

記述言語：英語   出版者・発行元：Pnas Nexus  

Phage therapy has emerged as a promising alternative to conventional antimicrobial therapy for antimicrobial-resistant bacterial infections, but concerns about uncontrolled phage proliferation have limited its use. To address this issue, we established a nonproliferative phage-based DNA delivery system, called bacteria-targeting capsid particle (B-CAP), for the development of antimicrobial agents which effectively prevented phage spread while maintaining bactericidal activity. B-CAP is principally a T7 phage capsids packaged with a partial T7 phage genome, giving it the allowance to accommodate large foreign DNA up to 18 kb in length. We confirmed the efficacy of B-CAP in targeting and injecting its genome into bacteria, analogous to the wild-type phage. To demonstrate proof-of-concept and potential for developing an antimicrobial agent, we loaded colicin E1 operon onto the B-CAP system, resulting in the construction of B-CAP_ColE1, an antimicrobial agent capable of boosting colicin E1-based bacterial killing against Escherichia coli. Although no therapeutic effect was observed for B-CAP, B-CAP_ColE1 exhibited strong bactericidal activity against carbapenem-resistant E. coli both in vitro and in vivo, and significantly improved the survival of mice in an infection mouse model experiment. Finally, B-CAP_ColE1 is biologically contained or inert, reducing potential biological hazards during therapeutic use. Our results demonstrate that the B-CAP system offers a new strategy for developing nonreplicative phage-based antimicrobial agents against bacterial infections.

DOI： 10.1093/pnasnexus/pgaf176

Web of Science

Scopus

PubMed

記述言語：英語   出版者・発行元：Jac Antimicrobial Resistance  

Background: Antimicrobial resistance is a global health challenge with profound implications across sectors. Livestock, a significant field at the One Health interface, lacks sufficient information, particularly in low-resource settings such as Malawi. Objectives: We determined the antimicrobial resistance rates of Escherichia coli isolated from broiler chickens in Malawi and explored the relationship between resistance genes across sectors using genomic analysis. Methods: In 2023, we isolated 115 E. coli strains from 116 faecal and caecal samples from broiler chickens across Malawi. Antimicrobial susceptibility tests were performed using agar dilution method according to the Clinical Laboratory Standard Institute guidelines. Whole-genome sequencing was performed using Illumina sequencing. Results: Notably, 50 isolates (44%) were resistant to cefotaxime. We detected ESBL bla<inf>CTX-M</inf> genes (bla<inf>CTX-M-55</inf>, bla<inf>CTX-M-14</inf>, bla<inf>CTX-M-65</inf>, bla<inf>CTX-M-27</inf>, bla<inf>CTX-M-15</inf>, bla<inf>CTX-M-1</inf>, and bla<inf>CTX-M-3</inf>) in 48 cefotaxime-resistant isolates, which exhibited higher resistance rates to levofloxacin than non-ESBL-encoding isolates (29/48; 60% versus 20/67; 30%). All isolates were susceptible to colistin and carbapenems. High resistance rates were observed for tetracycline and co-trimoxazole commonly used in broiler chickens (90% and 70%, respectively). Sequence type 206 and phylogroup A were predominant (14% and 65%, respectively). In the genetic context of bla<inf>CTX-M</inf> genes, whole-genome alignment of the ESBL-producing isolates with reference plasmids from E. coli of various origins indicated significant similarity. Conclusions: Antimicrobial resistance is highly prevalent among E. coli from broiler chickens in Malawi. Genomic analysis suggests potential transmission pathways for ESBL genes across sectors, necessitating further studies from One Health perspective.

DOI： 10.1093/jacamr/dlae200

Web of Science

Scopus

PubMed

CiNii Research

DOI： 10.1016/j.bbrc.2021.04.123

総ページ数：4  

CiNii Research

記述言語：英語   会議種別：シンポジウム・ワークショップ パネル（指名）