CRP and Alzheimer disease: Firmicutes (OTU254), Acidobacteriales bacterium (OTU324), indeterminate taxon (OTU555), Castellaniella alcaligenes (OTU376), Lachnospiraceae family taxon (OTU18) were negatively correlated with CRP, while Christensenellaceae R-7 (OTU228) and Klebsiella pneumoniae (OTU585) were positively correlated with the level of CRP in the blood of AD patients.