Table 1.

Signature Genera Deficient in Aged Mouse Microbiome Compared to Young Mice^a

Aged vs Young Mice At Baseline
Genus (Phylum)	Mean %Increase in Error on Removal (SD)	Relative Abundance in Young/ Aged Mice (P Value)b
Bacteroides (Bacteroidetes)	8.03 (0.98)	15.4%/0.3% (<.0001)
rc4-4 (Firmicutes)	6.26 (0.89)	0.7%/0.0% (<.0001)
Alistipes (Bacteroidetes)	4.11 (0.68)	0.2%/0.0% (<.0001)

Abbreviations: CDI, Clostridium difficile infection; SD, standard deviation.

^aTo investigate which components of the microbiota may be important in affecting CDI outcome, we identified signature genera that are the most important in determining the difference between young and age mice microbiota by random forest analysis.

^bWilcoxon rank-sum test.