The bacteriophage preparations which are used in the treatment procedures contain phages from the Bacteriophage Collection of the Institute of Immunology and Experimental Therapy of the Polish Academy of Sciences in Wrocław. For each patient only specific formulations of single phage or a phage mixture that are active against the pathogenic bacterial strain or strains isolated from the patient are used for the treatment.The isolation of live bacterial pathogen from the patient is necessary to carry out a phage-typing procedure to determine if the preparation of an active formulation is possible which is a prerequisite for receiving the treatment.