VSL#3 consists of sachets each containing 900 billion viable lyophilised bacteria, comprising 4 strains of Lactobacillus (L. paracasei, L. plantarum, L. acidophilus and L. delbrueckii subsp. bulgaricus), 3 strains of Bifidobacterium (B. longum, B. breve and B. infantis) and 1 strain of Streptococcus thermophilus, in maltose and silicon dioxide as excipients.