RESUMEN
This study was carried out to determine increased level of antibodies to certain bacteria in rheumatoid arthritis (RA) patients. Fifty RA patients and 25 each of those suffering from osteoarthritis (OA) and healthy controls were tested for antibodies to somatic ('O) and flagellar ('H') antigens of Proteus mirabilis, Escherichia coli, and for antibodies to 'O' antigen of Klebsiella pneumoniae by standard tube agglutination method. Anti-Proteus antibodies against 'O' and 'H' antigens could be demonstrated in 70% and 64% RA cases respectively, and were statistically significant. Antibodies could be demonstrated against E. coli 'O' and 'H' antigens in 86% and 92% RA cases respectively, and were statistically significant. Against K. pneumoniae 'O' antigen, no antibody could be demonstrated in any of RA and OA cases, and healthy controls. Of the 50 RA patients, 30 had raised CRP levels. Antibodies against P. mirabilis and E. coli antigens appeared to be independent from CRP. Thus a specific elevation in the immune response to P. mirabilis and E. coli has been demonstrated in patients with RA from India.