Infectious Diseases

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Email	iga-ryu◎t.mail.nagoya-u.ac.jp (Please send a message after replacing "◎" mark with "@" mark. )
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OUTLINE

Our team currently consists of one professor, three instructors, and three medical staff members (including one graduate student).

Our basic research focuses on the epidemiology, infection control, and treatment of healthcare-associated infections and their causative pathogens, with a particular emphasis on multidrug-resistant Gram-negative bacilli. Additionally, we conduct surveillance and genomic typing of viral infections within Neonatal Intensive Care Units (NICU).

In terms of clinical research, we conduct multicenter cross-sectional epidemiological studies to promote hospital infection control and antimicrobial stewardship. We are currently engaged in multicenter surveys regarding outpatient antimicrobial prescription patterns, as well as the analysis of real-world data concerning perioperative antimicrobial use.

RESEARCH PROJECTS

This translation is written in a formal, academic style suitable for a research website, laboratory profile, or annual report.

1. Epidemiological Research on Healthcare-Associated Infections and Antimicrobial Prescribing

i) Cross-sectional Epidemiological Surveys of Inpatients
We introduced the ""Point Prevalence Survey (PPS)"" for infection control for the first time in Japan to investigate the status of healthcare-associated infections (HAIs) and antimicrobial use. Following a 2016 multi-center study across four university hospitals, we conducted a PPS involving 10,199 patients from 27 hospitals in Aichi Prefecture. The results revealed an HAI prevalence of 6.6% (device-associated infections at 0.91%), with 29.6% of all inpatients receiving antimicrobial agents. Furthermore, this study reported on the actual status of perioperative antimicrobial administration and the epidemiology of pediatric antimicrobial use in Aichi Prefecture. These findings represent the largest hospital epidemiological dataset in Japan and contribute to the improvement of infection control measures and antimicrobial stewardship. Moving forward, we plan to expand these PPS activities from Aichi Prefecture to a nationwide scale.

Prevalence of healthcare-associated infections by bed capacity.

Drugs accounting for 75% of antimicrobial use and their indications.

ii) Research on Perioperative Antimicrobials
To identify issues in perioperative antimicrobial use, we surveyed 688 patients across 16 university hospitals in 2018. While 46.8% of patients overall received administration in accordance with guidelines, significant disparities in appropriate use were observed depending on the surgical specialty and facility. We are currently conducting research to evaluate the efficacy of perioperative antimicrobials using real-world data.

iii) Research on Outpatient Antimicrobial Prescribing
In fiscal year 2024, we conducted a survey of 2,987 individuals across 34 hospitals in Aichi Prefecture that have earned the ""Infection Control Enhancement Addition 1"" (Kansen-taisaku-kojo-kasan 1) to investigate inappropriate antimicrobial prescribing. Future plans include investigating the current status of outpatient antimicrobial administration using real-world data.

2. Analysis of Drug-Resistant Gram-Negative Bacilli

i) Analysis of Carbapenem-Resistant Enterobacterales (CRE)

The spread of CRE is becoming a global threat, and surveillance has commenced in Japan. Our laboratory conducts research on effective infection control measures and treatments for CRE, as well as molecular epidemiological analysis and drug-resistance mechanisms of CRE isolates detected in our hospital and regional surveillance.

We analyzed CRE isolates collected by the Council for Infection Control and Prevention at National and Public University Hospitals to identify factors associated with mortality and to analyze resistance genes and detected species.

We perform molecular epidemiological analysis on CRE strains where outbreaks are suspected within nearby facilities.

We utilize Next-Generation Sequencing (NGS) to analyze rare carbapenemase-producing organisms.

ii) Molecular Epidemiological Study of ESBL-Producing Klebsiella pneumoniae

Compared to E. coli, the isolation frequency of ESBL-producing Klebsiella pneumoniae is lower, and molecular epidemiological data remains scarce. In collaboration with Kyushu University and Asahikawa Medical University, our laboratory analyzed the ESBLs produced by these strains alongside their molecular and genetic characteristics. We found that the distribution of ESBL genes and quinolone resistance genes varied across the three geographic regions.

Cluster analysis regarding the distribution of ESBL-producing Klebsiella pneumoniae. Numbers indicate Sequence Types (ST). Circle size represents the number of isolates. Circle colors indicate the detecting university: Blue (Nagoya University Hospital), Green (Asahikawa Medical University Hospital), and Red (Kyushu University Hospital).

iii) Research on the Molecular Epidemiology, Resistance Mechanisms, and Clinical Presentation of the Enterobacter cloacae complex

The Enterobacter cloacae complex causes clinical conditions such as urinary tract and intra-abdominal infections, and resistance due to ESBL production or AmpC β-lactamase hyperexpression is a growing concern. As this complex consists of various subspecies, we collect and analyze isolates from multiple facilities to determine how resistance gene types, frequency of resistance, and clinical outcomes differ by subspecies.

3. Development of an Infectious Disease Management Support System (Joint Research with Shimadzu Corporation)

We developed a web-based communication system designed to streamline consultations regarding infectious disease clinical practice. By improving access to infectious disease specialists and contributing to earlier treatment decisions, the system aims to improve patient outcomes.

[Link: Development of Japan’s First ""Infectious Disease Management Support System"" through Industry-Academia Collaboration]

[Link: Interview: ""The Infectious Disease Management Support System Born from Field Needs is Launching Soon!""]

4. Research on Infection Control Derived from the Hospital Environment Focusing on Hand-Wash Sink Drains

To control infections originating from hospital hand-wash sinks, we are analyzing the microbiome on sink surfaces and within drainpipes. For bacterial contamination in drains, we are using the ""DrainPod,"" a drainpipe heating device developed by Moraine Corporation, to verify its effectiveness in reducing bacterial loads in existing piping, analyze deposits, and assess its impact on drain structure and safety. By combining culture methods, whole-genome sequencing, and endoscopic observation, we aim to establish infection control measures for the hospital environment that are grounded in clinical practice.

Verification of the disinfection effect of a drainpipe heating device on hospital hand-wash sink drains. It significantly reduced bacterial colony formation in existing pipes, and the antibacterial effect persisted with continuous use.

5. Research on Optimizing Alcohol-Based Hand Sanitizer Volume Using a Hand Hygiene Evaluation System

To improve the quality of hand hygiene in hospitals, we are conducting research using ""HandWe!"", a hand hygiene evaluation system developed by Moraine Corporation. In collaboration with infection control nurses, we are quantitatively evaluating the relationship between the volume of alcohol-based hand sanitizer, application coverage, and hand size to verify the optimal usage volume. We aim to establish practical, evidence-based hand hygiene techniques.

6. Research on Antibiograms for Medical Institutions and Clinics in Nagoya City

We are conducting a comparative analysis of microbial distribution and drug susceptibility using data from medical institutions in Nagoya with ""Infection Control Enhancement Addition 1"" and clinical data from the Falco Biosystems database. By comparing data from large-scale hospital groups with primary care clinics, we aim to construct antibiograms usable in primary care settings and establish optimal antimicrobial treatments tailored to real-world clinical practice.

7. Research on Optimizing Treatment for Bloodstream Infections Using Rapid Antimicrobial Susceptibility Testing (RAST)

We are conducting clinical microbiological research aimed at achieving rapid and appropriate antimicrobial therapy for bloodstream infections, which are severe infectious diseases. By establishing and operating RAST directly using positive blood culture samples in-hospital and validating it against the gold-standard broth microdilution method, we aim to optimize treatment rapidly. We plan to conduct multi-center joint research to build a system suited for the clinical landscape of bacteremia treatment in Japan.

8. Surveillance and Pathophysiological Analysis of Enterovirus/Parechovirus Infections in the Neonatal Intensive Care Unit (NICU)

While Enterovirus and Human Parechovirus infections are often mild or asymptomatic in children, they can become severe in neonates. However, identification of these virus species is not covered by insurance in Japan, making real-time clinical feedback difficult. We perform active surveillance using stool samples from patients in the NICU during epidemic periods via regular viral PCR assays. We also conduct genotyping to identify detected species and investigate factors involved in the progression to severe disease. 

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We welcome anyone interested in infectious disease research to contact us.