Immunological cross-reactivity between Enterobacter aerogenes and Klebsiella capsular polysaccharides.

Enterobacter aerogenes capsular polysaccharides (CPS) which cross-react with Klebsiella K3, K21, and K68 CPS were purified. Humans immunized with a vaccine containing Klebsiella K3 and K21 CPS produced antibody which recognized these E. aerogenes CPS. The magnitude of the immune response to the E. aerogenes CPS varied among the serotypes. Passive transfer of an immunoglobulin produced from the plasma of donors immunized with the above vaccine afforded significant protection against challenge with an E. aerogenes strain bearing a capsule which cross-reacts with Klebsiella K3 CPS.