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Updated: May 14, 2026
Operating and Biocontainment Procedures of a Facility for Laboratory Mice with a Natural Microbiome: Immunophenotyping Procedure
Published on: December 13, 2024
Current microbiological status of laboratory mice and rats in experimental facilities in Japan
Nobuhito Hayashimoto1, Hanako Morita, Tomoko Ishida
1ICLAS Monitoring Center, Central Institute for Experimental Animals, 3-25-12 Tonomachi, Kawasaki, Kawasaki, Kanagawa 210-0821, Japan.
Abstract:
On the basis of our 2011 microbiological monitoring tests, we report here the current microbiological status of mice and rats housed in experimental facilities in Japan. We tested more than 14,000 mice, 6,000 serum samples, 500 fecal or cecal samples, and 200 lung samples from 3,549 mouse facilities within Japanese universities and institutes (U/I), pharmaceutical companies and contract research organizations (P/C). We also tested more than 1,500 rats, 1,600 serum samples, and 20 fecal or cecal samples from 772 U/I and P/C rat facilities. Bacterial cultures, serology, microscopy, PCR, and DNA analysis using DNA chips were performed. Staphylococcus aureus (18.8% in mouse facilities, 58.6% in rat facilities) was the most prevalent agent in both the mouse and rat facilities. The next most prevalent agents in the mouse facilities were murine norovirus (11.97%), intestinal protozoa (0.05-8.49%, from various species), Pasteurella pneumotropica (5.32%), and Helicobacter hepaticus (3.17%), while intestinal protozoa (0.74-6.84% from various species), Syphacia muris (6.20%), Pseudomonas aeruginosa (3.61%), and Pasteurella pneumotropica (3.05%) were the subsequent most prevalent agents in the rat facilities. These results suggest that the currently prevalent microbes in laboratory mice and rats in Japan are mainly opportunistic pathogens, intestinal protozoa, and microbes with low pathogenicity.
Insights
Microbiological monitoring of laboratory animals in Japan revealed Staphylococcus aureus as the most common pathogen in both mice and rats. Opportunistic pathogens and low-pathogenicity microbes were prevalent, highlighting the need for continued surveillance in research settings.
Area of Science:
- Veterinary Microbiology
- Laboratory Animal Science
- Infectious Diseases
Background:
- Microbiological monitoring is crucial for maintaining the health and integrity of research animal populations.
- Understanding the prevalence of pathogens in laboratory rodents is essential for accurate experimental outcomes.
- Previous data on the microbiological status of Japanese laboratory animals is limited.
Purpose of the Study:
- To assess the current microbiological status of mice and rats in Japanese research facilities.
- To identify the most prevalent bacterial and protozoan agents affecting these animals.
- To provide baseline data for future comparative studies and improved animal welfare.
Main Methods:
- Conducted microbiological monitoring tests on over 14,000 mice and 1,500 rats from various Japanese research institutions.
- Utilized a combination of bacterial cultures, serology, microscopy, Polymerase Chain Reaction (PCR), and DNA chip analysis.
- Analyzed serum, fecal, cecal, and lung samples to detect a wide range of potential pathogens.
Main Results:
- Staphylococcus aureus was the most prevalent agent, found in 18.8% of mouse facilities and 58.6% of rat facilities.
- Key pathogens in mice included murine norovirus (11.97%) and Pasteurella pneumotropica (5.32%).
- In rats, intestinal protozoa (0.74-6.84%) and Syphacia muris (6.20%) were also significant findings.
Conclusions:
- The primary microbial agents in Japanese laboratory rodents are opportunistic pathogens, intestinal protozoa, and low-pathogenicity microbes.
- These findings underscore the importance of ongoing microbiological surveillance programs.
- Implementing effective control strategies is necessary to minimize the impact of these agents on research.
