This invention relates to a composition suitable for use in the prevention of opportunistic infections in immune-compromised individuals comprising a probiotic Bifidobacterium lactis, Bifidobacterium infantis, Bifidobacterium breve or Bifidobacterium longum and a fucosylated oligosaccharide selected from the group comprising 2'-fucosyllactose, 3'fucosyllactose, difucosyllactose, lacto-N-fucopentaose, lacto-N-fucohexaose, fucosyllacto-N-hexaose and fucosyllacto-N-neohexaose. The invention further extends to the use of such a composition in the prevention of opportunistic infections in immune-compromised individuals.