[Serologic diagnosis of Lyme disease in patients with undifferentiated arthritis. Diagnostic problems].

BACKGROUND: Arthritis is a frequent manifestation of Lyme disease. The diagnosis of this disease is especially supported by serological techniques which however have false positives or negatives. The aim of this study was to establish the frequency of serologies positive to Borrelia burgdorferi in patients with non-filiated arthritis and in other well defined rheumatic diseases.

METHODS: A prospective study was performed to detect antibodies (AB) versus Borrelia burgdorferi in 43 patients with undifferentiated arthritis and in 100 patients with articular disease of precise diagnosis (rheumatoid arthritis, systemic lupus erythematosus, psoriasis arthropathy, and reactive arthritis/Reiter's syndrome). The technique was performed by indirect immunofluorescence and was repeated by enzymoimmunoassay in doubtful or positive results. Titers greater than 1/256 were considered as positive.

RESULTS: Positive serology was found in two patients with undifferentiated arthritis and in one patient with Reiter's syndrome. None of the three patients referred the antecedent of erythema chronicum migrans. Positive serology was not observed in any of the patients with rheumatoid arthritis, systemic lupus erythematosus or psoriatic arthritis.

CONCLUSIONS: A small proportion of patients with undifferentiated arthritis or Reiter's syndrome presented positive serology at low titers versus Borrelia burgdorferi with the interpretation of these results being difficult. The frequency of seropositivity in rheumatoid arthritis and systemic lupus erythematosus is very low.