To investigate the oral microflora of patients with oesophageal squamous cell carcinoma (ESCC), saliva samples were collected from 20 patients with ESCC and 21 healthy controls. The V3-V4 region of 16S rDNA was amplified and sequenced by the Illumina MiSeq high-throughput sequencing platform. The final sequences were used for OTU analysis. Alpha and beta diversity analysis showed that the bacterial diversity and richness of the ESCC group were lower than those of the control group, while the variability of the ESCC group was higher than that of the control group. According to the Metastats difference analysis and LEfSe analysis, the high risk of ESCC may be related to Actinomyces and Atopobium, while the healthy control group is closely related to Fusobacterium and Porphyromonas (the analysis was performed at the genus level). The establishment of the relationship between oral microbiota and risk of ESCC may lead to significant advances in understanding the aetiology of cancer and may open a new research paradigm for cancer prevention.

Purpose: To investigate the genomic and plasmid characteristics of a newly discovered Pseudomonas stutzeri strain with a bla VIM-2 -carrying plasmid and novel integron In1998 isolated from a cerebrospinal fluid specimen in a teaching hospital. Methods: Species identification was performed by MALDI-TOF MS, and bla VIM-2 was identified by PCR and Sanger sequencing. Whole-genome sequencing analysis was conducted using the Illumina NovaSeq 6000 and Oxford Nanopore platforms. Integron detection was performed using INTEGRALL. The phylogenetic tree was constructed by using kSNP3.0. Plasmid characteristics were assessed by S1-pulsed-field gel electrophoresis (S1-PFGE), Southern blotting, conjugation experiments, and whole-genome sequencing analysis. Comparative genomics analysis of the plasmid and genetic context of bla VIM-2 were conducted by using BLAST Ring Image Generator (BRIG) and Easyfig 2.3, respectively. Results: ZDHY95, an MDR strain of P. stutzeri harboring bla VIM-2 , was identified. It was sensitive only to amikacin and was resistant to carbapenems, β-lactams, aztreonam, fluoroquinolones, and aminoglycosides. Joint S1-PFGE, Southern blot, conjugation assay, and whole-genome sequencing experiments confirmed that the bla VIM-2 gene was located within class I integron In1722 of the plasmid and that the surrounding genetic environment was 5ʹCS-aacA4ʹ-30-bla VIM-2 -aacA4ʹ-3ʹCS. The novel class I integron In1998 was detected on the chromosome of P. stutzeri ZDHY95, and the gene cassette array was 5ʹCS-aacA3-aadA13-cmlA8-bla OXA-246 -arr3-dfrA27 -3ʹCS. Phylogenetic analysis showed that antimicrobial resistance gene-carrying P. stutzeri isolates were divided into two clusters, mainly containing isolates from the USA and Pakistan. Conclusion:A novel bla VIM-2 -carrying conjugative plasmid, pZDHY95-VIM-2, was reported for the first time in P. stutzeri, elucidating the genetic environment and transfer mechanism. The gene structure of the novel class I integron In1998 was also clarified. We explored the phylogenetic relationship of P. stutzeri with drug resistance genes and suggested that Pseudomonas with metallo-β-lactamases (MBLs) in the hospital environment may cause infection in patients with long-term intubation or after interventional surgery.