The use of a dietary fiber or a mixture of dietary fibers for the manufacture of a composition, being a pharmaceutical composition or a functional food or a functional feed, for the prevention, the inhibition and/or the treatment of systemic infections in humans and in vertebrates caused by pathogenic bacteria is disclosed.A method for the prevention, the inhibition and/or the treatment of systemic infections in humans and in vertebrates caused by pathogenic bacteria, comprising administration to said beings, orally, through tube feeding or rectally, a composition containing an effective amount of a dietary fiber or mixture of dietary fibers is also disclosed.The dietary fiber is preferably a fructan, typically inulin and/or oligofructose, most preferably chicory inulin with an average degree of polymerization (DP) of at least 20.