Proteus antigen cross react with which of the following organism?: (A) Klebsiella, (B) Chlamydiae, (C) Rickettsiae, (D) E.coli
Answer is C. Proteus antigen cross react with Rickettsiae. Proteus antigens (OX19, OX2 & OXK strains) cross reacts with group specific lipopolysaccharide rickettsial antigens. This is the basis of Weil Felix (heterophile agglutination) test. It is used for diagnosis of rickettsial infections. The test detects anti-rickettsial antibodies that cross-react with O antigens of ceain non motile strains of Proteus.