Association of reactive arthropathy and Morganella morganii cross reacting with Yersinia enterocolitica.

Two patients exhibited reactive arthropathy in association with chronic diarrhoea and abdominal pain. Rising titres of agglutinating antibody to Yersinia enterocolitica O3 were observed in association with arthropathy. Morganella morganii was isolated from faeces of one patient in heavy growth. In both patients, absorption of the sera with morganella antigen abolished yersinia reactivity. Morganella titres were more than 8 times the yersinia titres and were unaffected by absorption with Yersinia. Neither patient had detectable antibody to the predominant enterobacterial species present in faeces. One patient developed acute cystitis with Proteus mirabilis and had no serological response to the proteus isolate. We conclude that the elevated morganella titres were specific. The role of M. morganii in intestinal disorders remains to be established, but from our findings, it should be added to the list of organisms associated with reactive arthropathy.