Klebsiella pneumoniae C3 lipopolysaccharide mutants obtained by resistance to bacteriophage FC3-9.

Bacteriophage FC3-9 is one of the several bacteriophages of Klebsiella pneumoniae C3 isolated in our laboratory. Mutants resistant to this bacteriophage were isolated and found to be devoid of lipopolysaccharide O antigen, modified in outer-membrane protein composition and sensitive to complement killing (serum-sensitive), unlike the wild-type strain. Serum-resistant mutants were isolated from these strains. They regained the lipopolysaccharide O antigen and the wild-type outer membrane protein composition and became sensitive to bacteriophage FC3-9.