Abstract:[Background] New pathogens that interfere with scientific research have been constantly discovered in laboratory animals. Corynebacterium kutscheri and Pseudomonas aeruginosa as pathogenic microorganisms affecting the health of laboratory animals are required to be monitored in the national standard. In this study, suspected strains of C. kutscheri and P. aeruginosa were isolated from specific pathogen-free (SPF) mice reared at the Laboratory Animal Center of Jilin University. [Objective] To identify the species and reveal the biological characteristics, phylogenetic relationship, and genomic characteristics of these pathogens, providing valuable biological resources and laying a foundation for developing reference materials and establishing an evaluation system for these pathogens. [Methods] The biological characteristics of the pathogens were studied by Gram staining, drug sensitivity test, and physiological and biochemical methods. PCR, phylogenetic analysis, whole genome sequencing, and bioinformatics analysis were performed to clarify the genetic characteristics of the strains. [Results] Through morphological observation, 16S rRNA sequencing, genome analysis, and phylogenetic analysis, the isolates were identified as C. kutscheri CCPM-B-B-019-2402-1 and P. aeruginosa CCPM-B-B-013-2402-3, respectively. C. kutscheri CCPM-B-B-019-2402-1 was resistant to oxacillin, nitrofurantoin, and benzylpenicillin. P. aeruginosa CCPM-B-B-013-2402-3 showed resistance to ticarcillin/clavulanic acid and tigecycline, while it demonstrated sensitivity to 9 antibiotics including ceftazidime, ciprofloxacin, and levofloxacin. The results obtained from whole genome sequencing indicated that C. kutscheri CCPM-B-B-019-2402-1 carried key virulence genes such as fagA, fagB, fagC, and fagD, whereas P. aeruginosa CCPM-B-B-013-2402-3 harbored virulence genes like plcB, tse6, and tse5. [Conclusion] In this study, two strains of pathogenic bacteria isolated from the tracheal tissue and cecum of SPF mice were identified, and their genomic characteristics were analyzed. This study provides important resources and support for the establishment of standard strains of pathogenic bacteria in laboratory animals, the development of reference materials of pathogenic bacteria in laboratory animals, and the quality control of laboratory animals.
