Sex differences associate with late microbiome alterations after murine surgical sepsis.

BACKGROUND: Sepsis-induced gut microbiome alterations contribute to sepsis-related morbidity and mortality. Given evidence for improved postsepsis outcomes in females compared with males, we hypothesized that female mice maintain microbiota resilience versus males. METHODS: Mixed-sex C57BL/6 mice underwent cecal ligation and puncture (CLP) with antibiotics, saline resuscitation, and daily chronic stress and were compared with naive (nonsepsis/no antibiotics) controls. For this work, the results of young (3-5 months) and old (18-22 months) adult mice were analyzed by sex, independent and dependent of age. Mice were sacrificed at days 7 and 14, and 16S rRNA gene sequencing was performed on fecal bacterial DNA. α and ß diversity were determined by Shannon index and Bray-Curtis with principal coordinate analysis, respectively. False discovery rate (FDR) correction was implemented to account for potential housing effect. RESULTS: In control mice, there was no difference in α or ß diversity between male and female mice (FDR, 0.76 and 0.99, respectively). However, male mice that underwent CLP with daily chronic stress had a decrease in microbiota α diversity at 7 days post-CLP (Shannon FDR, 0.005), which was sustained at 14 days post-CLP (Shannon FDR, 0.001), compared with baseline. In addition, male mice maintained differences in ß diversity even at day 14 compared with controls (FDR, <0.0001). In contrast, female mice had a decreased microbiota α diversity (Shannon FDR, 0.03) and ß diversity (FDR, 0.02) 7 days post-CLP but recovered their α and ß diversity by post-CLP day 14 (Shannon FDR, 0.5, and FDR, 0.02, respectively). Further analysis of females revealed that only young female mice were not different (ß diversity) post-CLP day 14 to controls. CONCLUSION: Although sepsis-induced perturbations of the intestinal microbiota occur initially in both male and female C57BL/6 mice, females demonstrate different microbiota by day 14. This may be seen primarily in younger females. This difference in recovery may play a role in outcome differences between sexes after sepsis.

A genomic analysis of Clostridium difficile infections in blunt trauma patients.

BACKGROUND: Evidence demonstrates that susceptibility to Clostridium difficile infection is related to host risk factors as much as bacterial potency. Using blood leukocyte genome-wide expression patterns of severe blunt trauma patients obtained by the National Institute of General Medical Sciences-sponsored Glue Grant Inflammation and the Host Response to Injury, we examined leukocyte genomic profiles of patients with C. difficile infection to determine preinfection and postinfection gene expression changes. METHODS: The genomic responses of 21 severe trauma patients were analyzed (5 C. difficile, 16 controls matched for age and severity of injury). After elimination of probe sets whose expression was below baseline or were unchanged, remaining probe sets underwent hierarchical clustering and principal component analysis. Molecular pathways were generated through Ingenuity Pathways Analysis. RESULTS: Supervised analysis demonstrated 118 genes whose expression in patients with C. difficile infection varied before and after their infection. Supervised analysis comparing patients with C. difficile infection with matched non-C. difficile patients before infection suggested that the expression of 501 genes were different in the two groups with up to 87% class prediction (p < 0.05). Many of these genes are related to cell-mediated immune responses, signaling, and interaction. CONCLUSION: Genomic analysis of severe blunt trauma patients reveals a distinct leukocyte expression profile of C. difficile both before and after infection. We conclude that an association may exist between a severe trauma patient's leukocyte genomic expression profile and subsequent susceptibility to C. difficile infection. Further prospective expression analysis of this C. difficile population may reveal potential therapeutic interventions and allow early identification of C. difficile-susceptible patients. LEVEL OF EVIDENCE: Prognostic/diagnostic study, level III.