Salmonella and E. coli are well-known bacteria that cause food poisoning, but less understood are species of Providencia, another causative agent of serious symptoms. Providencia rustigianii, isolated from pediatric gastroenteritis patients, has now undergone whole genome sequencing by a research team led by Osaka Metropolitan University Professor Shinji Yamasaki of the Graduate School of Veterinary Science and the Osaka International Research Center for Infectious Diseases.

Members of the team had previously reported that P. rustigianii carries a cytolethal distending toxin virulence gene on its plasmid. Elimination of this gene did not reduce the bacteria’s virulence, however.

This time, the whole genome sequencing revealed that P. rustigianii also possesses a virulence factor called the type III secretion system, which bears the highest degree of similarity to the gene found in Salmonella. The type III secretion system was found to be directly involved in cell invasiveness and enterotoxicity, making it a major virulence factor for P. rustigianii.

“Using the pathogenicity gene discovered in this study as an indicator, we plan to create a detection system for pathogenic species of Providencia in wild animals, water, livestock, and food, which can be expected to be useful in investigating natural hosts, sources of infection, and infection routes,” Professor Yamasaki exclaimed. “In addition, clarification of the pathogenic mechanism by the type III secretion system is expected to lead to the development of therapies that do not use antimicrobial agents.”

The findings were published in mBio.

Funding
This work was supported in part by JSPS KAKENHI 20K07483 to S.Y. and by Health and Labor Sciences Research grant number JPMH23KA1003 to S.Y.

Conflict of Interest
The authors declare no conflict of interest.

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