Provided is a kit or a system including two elements or components. The first component (i) is a selective component including a nucleic acid sequence and at least one proto-spacer. The second component (ii) includes at least one sensitizing component including at least one cas gene and at least one CRISPR array. At least one spacer of the CRISPR targets a proto-spacer included within a pathogenic gene of a bacterium so as to specifically inactivate said pathogenic gene in said bacterium and wherein at least one spacer of said CRISPR targets a proto-spacer included within said selective component of (i) so as to specifically inactivate said selective component. Further provided is a method using the components or kits of the invention for interference with a horizontal transfer of a pathogenic gene between bacteria and for preventing a pathologic condition in a mammalian subject caused by a bacterial infection.