Altered gut microbiota composition and its clinical correlations in patients with severe pneumonia: a single-center observational study in China

Abstract

Severe pneumonia in intensive care unit (ICU) patients is frequently accompanied by alterations in the gut microbiota. To explore the characteristics of the gut microbiota in these patients, we conducted an observational study comparing 38 patients with severe pneumonia to 34 healthy participants. We used 16S rRNA gene sequencing to profile their gut microbiota and analyze its correlation with clinical parameters. Our results show a significant dysbiosis in the gut microbiota of severe pneumonia patients, characterized by reduced diversity and notable shifts in microbial composition. Specifically, the study revealed an increase in potentially harmful bacteria like Enterococcus and a decrease in potentially beneficial bacteria such as Megamonas and Faecalibacterium. Functional analysis showed an upregulation of pathways for Staphylococcus aureus infection and valine, leucine, and isoleucine degradation in the severe pneumonia group compared to the healthy control group. Furthermore, our analysis found positive correlations between certain bacteria and clinical indicators. Megamonas abundance correlated positively with prealbumin levels, a marker of nutritional status. Bifidobacterium showed a positive correlation with white blood cell (WBC) count, and Blautia was positively correlated with the duration of mechanical ventilation. These findings suggest that gut microbiota dysbiosis may play a role in the progression of severe pneumonia, highlighting the potential for targeted therapies in this patient population.