[Infection and reactive arthritis: clinico-bacteriological correlation in seronegative arthropathies].

The aim of this study was to search infections that trigger reactive arthritis. Eighty-six patients with seronegative arthritis (SNA) were studied; 32 had reactive arthritis, 21 ankylosing spondylitis, 7 psoriatic arthritis and 26 undifferentiated seronegative oligoarthritis. As controls, 70 patients with connective tissue diseases (CTD) and 55 healthy volunteers (HV) were studied. Serological evidence for infection with Chlamydia trachomatis was studied with micro immunofluorescence, looking for L2 and BED serotypes and serological evidence for Yersinia infection, using a commercial kit. Stool cultures were done in seven patients with recent diarrhea, and endourethral or endocervical cultures in 35 individuals. Serotypes L2 or BED were positive in 23 of 83 patients with SNA, 3 of 39 patients with CTD and 4 of 55 HV (p < 0.03). IgG class antibodies against L2 were detected in 17% of SNA patients, 2.6% of CTD patients and 5.4% of HV (p < 0.05). IgM class antibodies were detected in 6 SNA patients, 0 CTD patients and 2 HV (NS). Twelve of 35 cultures were positive for Chlamydia. As a whole 30% of SNA patients has serological or bacteriological evidence for Chlamydia infection. Serology for Yersinia was positive in 39 of 81 SNA patients, 1 of 54 CTD patients and 3 of 51 HV (p < 0.01). Rates of infections were similar among male, female, HLA B27 positive and HLA negative subjects. It is concluded that SNA patients have a high prevalence of infections by Chlamydia trachomatis or Yersinia enterocolitica.