Research

Research Introduction1: Research on infectious diarrhea

In India, diarrhea caused by various pathogens (such as Vibrio cholerae, Shigella spp., pathogenic Escherichia coli, and Campylobacter spp., rotavirus and norovirus) are widespread. In Japan, where the infrastructure for daily life is well developed, the term "infectious diarrhea" may not be familiar to many. However, there is an increasing need to study these pathogens as causative microorganisms of travelers' diarrhea, as well as from the perspective of food hygiene management, such as contamination of imported foods. Our unit is approaching to clarify the actual situation of infectious diarrhea in developing countries, including India, by making full use of a variety of methods, including epidemiological surveys of diarrhea, genomic and metagenomic analysis of pathogens, and meta-analysis of pathogens and diarrhea using literature information. In particular, we are actively conducting research on asymptomatic carriers of V. cholerae (people carrying the pathogen but having no symptoms) and are accumulating interesting new knowledge.

Research Introduction2: Research on mutation and drug resistance of Vibrio cholerae

Kolkata city of our unit's research site is one of the epicenters of global cholera epidemic that continues to this day. Taking advantage of the fact that V. cholerae are readily available in this area, we systematically collect a large number of cholera bacteria from hospitalized patients for use in our research. Current research focuses on the analysis of antibiotic resistance and genetic changes over time in V. cholerae, as well as elucidating the toxins and factors involved in the toxicity and pathogenicity of epidemic strains at the genetic level. In parallel, we are also conducting research to clarify the mechanism of genome evolution of V. cholerae through analysis using next-generation sequencers. Through such research, we hope to develop efficient methods of controlling and preventing cholera.

Research Introduction3: Evaluation of PCR-based ORF Typing Analysis for Carbapenem-resistant Enterobacter species

Enterobacter species represent clinically significant pathogens associated with nosocomial infections and exhibit high frequency of carbapenem resistance. Historically, pulsed-field gel electrophoresis (PFGE) was the sole methodology available for strain homology determination; however, its implementation within hospital laboratories is impractical due to procedural complexity and substantial cost implications. Recently, PCR-based ORF Typing (POT) analysis, which can be performed within routine microbiological laboratory parameters, has been developed specifically for Enterobacter species; nevertheless, its clinical efficacy remains incompletely elucidated. This investigation aims to evaluate the utility of POT analysis for carbapenem-resistant Enterobacter species.

Research Introduction4: Prevalence Analysis of Cefiderocol-resistant Strains Among Carbapenem-resistant Enterobacterales (CRE)

Carbapenem-resistant Enterobacterales (CRE) represents the most critical antimicrobial-resistant pathogens, designated as "Priority 1" in the World Health Organization's antimicrobial resistance priority list. While cefiderocol, a novel antimicrobial agent developed and marketed in Japan, has demonstrated efficacy against various drug-resistant Gram-negative bacilli, its effectiveness against domestically isolated CRE strains remains insufficiently characterized. This study aims to provide antimicrobial susceptibility data for clinical CRE isolates obtained within Okayama Prefecture and to elucidate the genetic mechanisms underlying cefiderocol resistance in resistant strains.

Research Introduction5: Epidemiological Investigation of CRE in Okayama Prefecture and Adjacent Regions

With the substantial increase in inbound population, the risk of importation of antimicrobial-resistant organisms from international sources has progressively escalated; however, the current epidemiological status of CRE within Okayama Prefecture and surrounding regions remains predominantly undetermined. Through collaborative research with the Okayama Medical Laboratory Center, this investigation will implement screening cultures for CRE/ESBL-producing organisms and conduct comprehensive genomic analysis, including whole-genome sequencing.

Research Introduction6: Development of Rapid Diagnostic Methods for Enteric Viruses in India: Addressing Diarrheal Diseases and Public Health

In India, enteric viruses such as rotavirus, norovirus, and enterovirus are major causes of diarrheal diseases, widely prevalent across the country.These viruses significantly impact children's health and rural public health, while their relevance in traveler’s diarrhea and food contamination underscores the growing need for research. We aim to develop novel rapid diagnostic methods targeting viral RNA or proteins of these prevalent enteric viruses in India. This will contribute to elucidating the reality of viral infections in regions with limited medical infrastructure.