The invention provides a new antibiotic containing simulacrum antibody. The antibiotic consists of colicin E1, Ia, Ib, A, B, N, or aqueous channel-forming structural domain and the simulacrum antibody which is covalently linked to the carboxyl terminal of the peptide chain of said colicin or aqueous channel-forming structural domain. The simulacrum antibody is formed by the carboxyl terminal of the heavy chain variable (VH) complementarity determining region (CDR) 1 of immunoglobulin connected with the amino terminal of the VH framework region (FR) 2 where the carboxyl terminal is further connected with the amino terminal of the light chain variable (VL) CDR, and the immunoglobulin specifically recognizes the bacterial porin. The antibiotic is useful for preparing antibacterial agents such as anti-Neisseria meningitides, anti-vancomycin-resistant Enterococcus, anti-methicillin-resistant Staphylococcus aureus or anti-multiple drug resistant Pseudomonas aeruginosa.
