Gut microbiota composition in patients with colonization is not well investigated. We aimed to identify bacterial signatures associated with resistance and susceptibility to colonization (CDC) and infection (CDI). Therefore, gut microbiota composition from patients with CDC ( = 41), with CDI ( = 41), and without CDC (controls, = 43) was determined through 16S rRNA gene amplicon sequencing. Bacterial diversity was decreased in CDC and CDI patients (p<0.01). Overall microbiota composition was significantly different between control, CDC, and CDI patients ( = 0.001). Relative abundance of (most likely ) increased stepwise from controls to CDC and CDI patients. In addition, differential abundance analysis revealed that CDI patients' gut microbiota was characterized by significantly higher relative abundance of and than CDC patients and controls. Control patients had significantly higher and abundance than colonized patients. Network analysis indicated that was negatively associated with in CDI patients, while was positively associated with in CDC patients. Bacterial microbiota diversity decreased in both CDC and CDI patients, but harbored a distinct microbiota. and may indicate resistance against colonization and subsequent infection, while may indicate susceptibility to colonization and infection by .