Abstract
A method is described for producing monovalent and polyvalent vaccines from culture filtrates of Klebsiella aerogenes. With a single injection, each monovalent vaccine protected mice against lethal intraperitoneal challenge by more than 30 capsular types; and polyvalent vaccines containing 2-12 monovalent components protected against 46-61 of the 77 capsular types of K. aerogenes. One vaccine with 12 components, administered in two doses, induced full protection against 71 types and protected half of the mice challenged with the other six types.