Related Experiment Video
Updated: Jul 6, 2026
Rapid and Specific Detection of Acinetobacter baumannii Infections Using a Recombinase Polymerase Amplification/Cas12a-based System
Published on: April 25, 2025
Detection of Streptobacillus spp. in feral rats by specific polymerase chain reaction
Masanobu Kimura1, Tsutomu Tanikawa, Michio Suzuki
1Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan.
Abstract:
Streptobacillus moniliformis is an etiological agent of rat-bite fever and Haverhill fever in human infection. As the currently available methods for identifying the causative bacteria are not satisfactory, we attempted to establish them by PCR using newly designed primers for the 16S rRNA gene of S. moniliformis. We then determined the prevalence of Streptobacillus spp. in two species of feral rats that inhabit an urban region in Japan, because information on the prevalence of the bacteria in feral rats is obscure. The use of PCR with newly designed primers showed that an extremely high proportion of R. norvegicus harbored the bacteria (61/66, 92%), whereas the prevalence was only 58% in R. rattus (30/52). The nucleotide sequence analysis of the 16S rRNA gene of Streptobacillus spp. isolated from oral swabs of feral rats showed at least two different types of bacteria among isolates from R. norvegicus and R. rattus.
Insights
A new PCR method effectively detected Streptobacillus moniliformis, a cause of rat-bite fever. This bacterium is highly prevalent in Japanese urban rats, particularly Rattus norvegicus.
Area of Science:
- Microbiology
- Infectious Diseases
- Veterinary Medicine
Background:
- Streptobacillus moniliformis causes rat-bite fever and Haverhill fever in humans.
- Current diagnostic methods for S. moniliformis are insufficient.
- Prevalence data of Streptobacillus spp. in feral rat populations is limited.
Purpose of the Study:
- To develop a PCR-based diagnostic method for S. moniliformis.
- To investigate the prevalence of Streptobacillus spp. in feral rats in Japan.
- To analyze the genetic diversity of Streptobacillus spp. in rats.
Main Methods:
- Designed new primers targeting the 16S rRNA gene of S. moniliformis for PCR detection.
- Collected oral swabs from two species of feral rats (Rattus norvegicus and Rattus rattus) in an urban Japanese region.
- Performed nucleotide sequence analysis of the 16S rRNA gene from isolated Streptobacillus spp.
Main Results:
- PCR successfully identified S. moniliformis.
- High prevalence of S. moniliformis detected in Rattus norvegicus (92%) and Rattus rattus (58%).
- Sequence analysis revealed at least two distinct types of Streptobacillus spp. in isolates from both rat species.
Conclusions:
- The developed PCR method is effective for identifying S. moniliformis.
- Feral rats, especially R. norvegicus, are significant reservoirs for S. moniliformis in urban environments.
- Genetic diversity exists within Streptobacillus spp. circulating in rat populations.
