The role of the O-antigen lipopolysaccharide and capsule on an experimental Klebsiella pneumoniae infection of the rat urinary tract.

We obtained, by different methods, isogenic lipopolysaccharide (O antigen) and capsular polysaccharide (K antigen) mutants from Klebsiella pneumoniae strains able to induce experimental infections (cystitis and pyelonephritis) in rats. We compared the induction of experimental infections in rats by wild-type strains and the lipopolysaccharide and capsular polysaccharide mutants. The high-molecular mass lipopolysaccharide of K. pneumoniae is clearly implicated in the infection process of the rat urinary tract, whilst the capsular polysaccharide seems not to be involved to the same extent.