Abstract:

Objective To investigate the relationship between the differential expression of gut microbiota structure and prognosis in patients with septic shock. Methods Totally，81 critically sick patients were enrolled，including 34 cases of septic shock，who were either directly admitted to the intensive care unit（ICU）or transferred to the ICU from wards from January 2020 to January 2022. Perirectal swabs were collected from the patients during ICU admission. The gut microbiota was assessed by sequencing the V3-V4 hypervariable region of the 16S rRNA gene. Beta diversity，operational taxonomic units（OTU）and interactions of gut microbiota with the variables in the study were analyzed. OTU specifically associated with sepsis were researched in linear mixed models. Results Compared with non-septic shock group，age，C-reactive protein（CRP）level，sequential organ failure assessment（SOFA）score，acute physiology and chronic health evaluationⅡ（APACHEⅡ）score and ICU stay time were increased in septic shock group（P<0.05）. The diversity of gut microbiota was lower in the patients with septic shock（P=0.006 for Shannon's index，P<0.001 for Simpson's reciprocal）. There was a significant difference in Beta diversity between septic shock group and non-septic shock group（pseudo F=1.19，P=0.038）. After performing a linear mixed model analysis，24 OTU associated with septic shock could be retrieved，with Parabacteroides distasonis，Bilophila spp. being significantly higher in septic shock patient samples than in non-septic shock patient samples. In septic shock patients，Ezakiella and Megasphaera decreased. Conclusions Lower presence of beneficial genera and higher abundance of pathogens are observed in septic shock patients. Therefore，specific gut microbiota characteristics could predict sepsis development in ICU patients.

Key words: Gut microbiota, Septic shock, Intensive care unit