First Isolation, Identification, and Whole-Genome Sequencing of a Multidrug-Resistant Bovine-Derived Providencia...

Providencia stuartii is an opportunistic pathogen associated with multidrug resistance. However, its occurrence, genomic characteristics, antimicrobial resistance profiles, and pathogenic potential in cattle-associated isolates remain poorly understood.

A P. stuartii strain was isolated from a rectal swab of a diarrheic beef cattle individual during bacterial investigation on a commercial farm in Anhui Province, China. The strain was identified by Gram staining, biochemical tests, 16S rRNA sequencing, and whole-genome sequencing. Antimicrobial susceptibility was assessed using the Kirby-Bauer method, and resistance and virulence genes were detected by PCR and genomic analysis. Pathogenicity was evaluated in a murine infection model.

The isolate was confirmed as P. stuartii, with a 4.22 Mb genome and 41.28% GC content. It showed multidrug resistance, including resistance to eight antimicrobial agents. Genomic analysis revealed multiple resistance and virulence determinants, genomic islands, prophages, and CRISPR regions. Under high-dose intraperitoneal challenge conditions, the isolate caused dose-dependent mortality, systemic recovery from major organs, and histopathological lesions in mice.

This study reports the genomic and antimicrobial resistance characteristics of a multidrug-resistant P. stuartii strain recovered from a rectal swab of diarrheic beef cattle in China. High-dose intraperitoneal inoculation demonstrated that the isolate possessed pathogenic potential in mice under experimental conditions. However, the murine model did not reproduce natural exposure in cattle, and the findings do not establish bovine tissue invasion, clinical pathogenicity, or a causal role in diarrhea. Further epidemiological investigations and cattle-relevant experimental studies are required to determine the clinical significance of this organism in bovine populations.