Analysis of blood microbiota in patients with adult-onset Still's disease and sepsis by metagenomic next-generation sequencing

Aims/Background Adult-onset Still's disease (AOSD) shares similar clinical symptoms with sepsis. Thus, differentiating between AOSD and sepsis presents a great challenge while making diagnosis. This study aimed to analyse the changes in blood microbiota related to AOSD and sepsis using metagenomic next-generation sequencing (mNGS), identify potential biomarkers that distinguish AOSD from sepsis, and explore the diagnostic value of mNGS in differentiation between these two pathological conditions. Methods Clinical data of four AOSD patients and four sepsis patients treated in the Department of Rheumatology and Immunology, The Affiliated Hospital of Xuzhou Medical University between October 2021 and February 2022 were collected. The mNGS diagnostic records of these patients were analysed for microbial correlations in terms of species taxonomic structure and beta diversity by comparing blood microbiota between AOSD and sepsis. The biomarkers with the strongest capability in distinguishing the subgroups were screened using a random forest algorithm. Results There was no statistically significant differences between AOSD patients and sepsis controls in terms of gender and age (p > 0.05). A total of 91 operational taxonomic units (OTUs) were obtained. At the level of phylum, Proteobacteria, Ascomycota and Basidiomycota were present in high abundances in both groups (79.76%, 14.18% and 3.30% vs 54.03%, 32.77% and 5.81%). At the genus level, the abundances of Parainfluenzae, Aspergillus and Ralstonia were the top three highest in the AOSD group (73.88%, 10.92% and 5.48%), while Ralstonia, Aspergillus and Malassezia were ranked as the top three in the sepsis group in term of abundance (48.69%, 27.36% and 5.52%). In beta-diversity analysis, there were advances shown in visual principal coordinates analysis (PCoA) and non-metric multidimensional scaling (NMDS) between the AOSD group and sepsis group (p < 0.05), with little significant differences in the analysis of similarities (Anosim) (p > 0.05). Linear discriminant analysis effect size (LEfSe) showed that Mucoromycota, Saccharomycetes, Moraxellales, Mucorales, Xanthomonadales, Saccharomycetales, Acinetobacter, Stenotrophomonas, Yarrowia, Apophysomyces, Acinetobacter johnson, Yarrowia lipolytica, Apophysomyces variabilis and Stenotrophomonas maltophilia were more enriched in sepsis group (p < 0.05). The top five variables with the strongest capability in distinguishing between AOSD and sepsis were Acinetobacter johnsonii, Apophysomyces variabilis, Propionibacterium acnes, Stenotrophomonas maltophilia and Yarrowia lipolytica. Conclusion The blood microorganisms in AOSD were different from sepsis, and mNGS was potential to distinguish between AOSD and sepsis.