Anti-microbial biotherapeutic agents: alternatives to conventional pharmaceutical antibiotics

Abstract

Novel antimicrobial agents that can serve as replacements to conventional pharmaceutical antibiotics are disclosed. The antimicrobial agents comprise conjugatively transmissible plasmids that kill targeted pathogenic bacteria, but are not harmful to donor bacteria. Two types of lethal transmissible plasmids are disclosed. One type kills recipient bacteria by unchecked (“runaway”) replication in the recipient cells and is prevented from occurring in donor cells. Another type kills recipient bacteria by expressing a gene that produces a product detrimental or lethal to recipient bacterial cells, that gene being prevented from expression in donor cells.

We claim: 
     
         1 . A method for treating a recipient bacterium, comprising conjugatively transferring into said recipient bacterium a recombinant transmissible plasmid configured to express a killer gene in said recipient bacterium wherein expression of said killer gene in said recipient bacterium is lethal to said recipient bacterium. 
     
     
         2 . The method of  claim 1 , wherein said conjugatively transferring comprises exposing said recipient bacterium to a donor bacterium comprising said recombinant transmissible plasmid, wherein said donor bacterium is configured to conjugatively transfer said recombinant transmissible plasmid to a recipient bacterium. 
     
     
         3 . The method of  claim 1 , wherein said recombinant transmissible plasmid comprises at least one killer gene. 
     
     
         4 . The method of  claim 3 , wherein said donor bacterium is unaffected by expression of said at least one killer gene. 
     
     
         5 . The method of  claim 4 , wherein said donor bacterium represses expression of said at least one killer gene. 
     
     
         6 . The method of  claim 3 , wherein said at least one killer gene comprises a gene of a bacteriophage. 
     
     
         7 . The method of  claim 5 , wherein said bacteriophage is selected from the group consisting of T-series phages, Pl, p22 and λ. 
     
     
         8 . The method  claim 2 , wherein said donor bacterium comprises one or more transfer genes. 
     
     
         9 . The method of  claim 8 , wherein said one or more transfer genes are contained on said recombinant transmissible plasmid. 
     
     
         10 . The method of  claim 8 , wherein said donor bacterium further comprises a helper plasmid, wherein said one or more transfer genes are contained on said helper plasmid. 
     
     
         11 . The method of  claim 8 , wherein said one or more transfer genes are transfer genes of a plasmid selected from the group consisting of F, R6K and Ti. 
     
     
         12 . The method of  claim 1 , wherein said recombinant transmissible plasmid comprises an origin of transfer. 
     
     
         13 . The method of  claim 2 , wherein said donor bacterium is non-pathogenic. 
     
     
         14 . The method of  claim 2 , wherein said donor bacterium is selected from the group consisting of  Escherichia coli, Lactobacillus  spp.,  Lactococcus, Bifidobacteria, Eubacteria , and bacterial minicells. 
     
     
         15 . The method of  claim 1 , wherein said recipient bacterium is a pathogenic bacterium. 
     
     
         16 . The method of  claim 1 , wherein said recipient bacterium is Gram-negative. 
     
     
         17 . The method of  claim 1 , wherein said recipient bacterium is Gram-positive. 
     
     
         18 . The method of  claim 1 , wherein said bacterium is a selected from the group consisting of  Campylobacter  spp.,  Enterobacter  spp.,  Enterococcus  spp.,  Escherichia coli, Gardnerella vaginalis, Haemophilis  spp.,  Helicobacter pylori, Mycobacterium tuberculosis, Propionobacter acnes, Pseudomonas aeruginosa  and other  Pseudomonas  spp.,  Salmonella typhimurium, Shigella  spp. and  Staphylococcus  spp.