Antisense antibacterial method and compound

A method of inhibiting the growth of Escherichia coli, Salmonella typhimurium, or Yersinia pestis pathogenic bacterial cells, comprising exposing the bacterial cells to a growth-inhibiting amount of an antisense oligonucleotide compound, composed of morpholino subunits and phosphorus-containing intersubunit linkages joining a morpholino nitrogen of one subunit to a 5′ exocyclic carbon of an adjacent subunit, and having:

• (i) no more than 12 nucleotide bases,
• (ii) a targeting nucleic acid sequence of no fewer than 10 bases in length that is complementary to a target sequence containing or within 10 bases, in a downstream direction, of the translational start codon in SEQ ID NO:
• 2;
• and
• (iii) a Tm, when hybridized with the target sequence, between 50° to 60° C.;
• wherein said morpholino subunits in the oligonucleotide compound are joined by a combination of (a) uncharged phosphorodiamidate linkages, in accordance with structure I,
• where Y1═O, Z=O, Pj is a purine or pyrimidine base-pairing moiety effective to bind, by base-specific hydrogen bonding, to a base in a polynucleotide, and X is amino or alkyl amino, including dialkylamino;
• and
• (b) cationic phosphorodiamidate linkages in accordance with structure I, where Y1═O, Z=O, and Pj are as defined above, and X is 1-piperazino;
• and wherein said cationic linkages make up no more than about half the total number of linkages.