[A 2-year evaluation of antibacterial serology adapted to the diagnosis of reactive arthritis (168 cases)].

The diagnosis of reactive arthritis requires the identification of a trigger infection. Since 1984 we have carried out a series of serological tests that we have called "serology of reactive arthritis": they aim at detecting antibodies against the most common infectious agents in this particular pathology. This serology is essentially based on the complement-fixation test. Here we report the results obtained over a period of two years, comparing them with clinical and biological data: 168 cases have been studied. They include to two groups of patients: group A reassembling seronegative spondylarthropathies and including reactive arthritis (N = 104), and group B with patients suffering from a typical rheumatic affection usually having no relation to spondylarthropathies (N = 64). We propose for each antigen a level of positivity from which the presence of antibodies can be taken into consideration as part of the diagnosis. With reference to these levels we have obtained a significant relationship to recent antecedents (genito-urinary and intestinal), to the presence of IgM circulating immune complexes and to the precocity of the serological tests. The contribution of this type of serology to the recognition of reactive arthritis has been studied together with the other diagnosis factors of the diseases. We have been able to show significant rates of antibodies in more than 50% of the cases. The negative results and limits of this serodiagnosis are discussed.