Identification and Biological Characteristics of Rare Pathogen Comamonas kerstersii in the First Case of Gallbladder Puncture Fluid.

Comamonas kerstersii is an environmental microorganism, and clinical infections caused by this species are rare. In this study, the strain CXZJT123 was isolated from gallbladder puncture fluid and identified using a comprehensive approach including morphological observation, mass spectrometry, biochemical identification, 16S rRNA sequencing, and whole-genome sequencing. The morphological characteristics of CXZJT123 were consistent with the Comamonas. Mass spectrometry initially identified the strain as Comamonas aquatica, while biochemical assays demonstrated key features aligning with the Comamonas genus. Phylogenetic analysis of 16S rRNA sequences placed CXZJT123 in the same clade as C. kerstersii (NR 025530.1). Whole-genome sequencing followed by gene annotation using the Non-Redundant Protein Database (NR) revealed the highest gene homology with C. kerstersii. Further genomic analysis using the Virulence Factors of Pathogenic Bacteria (VFDB) and the Comprehensive Antibiotic Research Database (CARD) identified the presence of virulence genes, including those encoding flagella (flg series) and biofilm formation (pil series), as well as antibiotic resistance genes such as macB, arlR, and evgS. This study presents the first reported isolation of C. kerstersii isolated from gallbladder puncture fluid. The findings contribute valuable insights into the identification, genomic characteristics, and potential pathogenicity of C. kerstersii, providing a useful reference for the diagnosis and management of related infections.