The present invention refers to pharmaceutical products comprising immunogenic compositions for modulating the immune system, which comprise a therapeutically effective amount of a Immunological Response Shifter (IRS) comprising two or more immunoactive antigenic agents presenting pathogen-associated molecular patterns (PAMPS) and/or danger associated molecular patterns (DAMPS) and/or Stress Response Signals (SRS), in association with an antibiotic and one or more physiologically acceptable carriers, excipients, diluents or solvents. IN other embodiments, the present invention refers to methods to treat severe bacterial infections, sepsis and modulating the immune system.