1. A pharmaceutical composition comprising or, alternatively, consisting of at least one bacterial strain belonging to one or more than one species selected from the group comprising or, alternatively, consisting of Lactobacillus delbrueckii, Lactobacillus delbrueckii subsp. delbrueckii, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus pentosus, Lactobacillus reuteri and Bifidobacterium breve capable of producing bacteriocins and / or metabolites and / or hydrogen peroxide for use in a prophylactic and / or therapeutic pathogen and / or therapeutic pathogen belonging to the species E. coli, Clostridium difficile, Listeria monocytogenes, Enterococcus sp. and Klebsiella sp. 2. The composition of claim 1, wherein said bacterial strains are active against the E. coli pathogen； said pathogen is preferably selected from a serotype of E. coli O157: H7 and E. coli O104: H4； or from the group consisting of E. coli ATCC 8739, E. coli ATCC 10536, E. coli ATCC 35218 and E. coli ATCC 25922.3. The composition of claim 1, wherein said bacterial strains are active against the pathogen Listeria monocytogenens, strain ATCC 19112.4. The composition of claim 1, wherein said bacterial strains are selected from the group consisting of or, alternatively, consisting of: - B. breve BR03 DSM 16604- B. breve B632 DSM 24706- L. rhamnosus LR04 DSM 16605- L. rhamnosus LR06 DSM 21981 - L. plantarum LP01 LMG P-21021- L. plantarum LP02 LMG P-21020- L. plantarum LP03 LMG P-21022- L. plantarum LP04 LMG P-21023- L. pentosus LPS01 DSM 21980- L. delbr. subsp. delbrueckii LDD01 DSM 22106- L. reuteri LRE01 DSM 23877- L. reuteri LRE03 DSM 23879； preferably the composition contains or, alternatively, consists of two, or three, or four, or five or six strains belonging to one or more than one mind. 5. The composition of claim 4, wherein said bacterial strains are selected from the group consisting of or, alternatively, consisting of: - B. breve BR03 DSM 16604- B. breve B632 DSM 24706- L. rhamn
