Baseline microbiota composition modulates antibiotic-mediated effects on the gut microbiota and host

A study aiming to determine if mice humanized by different donors have different gut microbiota and colonic gene expression patterns in response to the administration of a commonly prescribed, broad-spectrum antibiotic (co-amoxiclav). Male, germ-free mice were humanized by one of two healthy, unrelated human donors. 56 days later, gut microbiota and colonic transcriptome samples were analyzed at baseline, by 454 pyrosequencing and Agilent microarray, respectively. Antibiotics were then administered for 7 days, following by repeated sampling of both the microbiota and colonic RNA at days 8, 11 and 18. Results of the microbiota analysis revealed marked shifts in the composition of one donor group in response to antibiotics and not the other donor group. Transcriptomics revealed a more conserved response, however the magnitude of the effect was greater in the donor group that had a greater shift in the microbiota. Humanization of germ-free mice by one of two unrelated human donors, (n=30; 15 mice per group) followed by antibiotic challenge and mapping of the microbiota and host response. 3 mice in each donor group at baseline and 4 mice in each group at the subsequent time points (days 8, 11 and 18).