Detection of borrelian DNA in synovial fluid for diagnosis of Lyme arthritis

Aim: To test sensitivity and specificity of a polymerase chain reaction (PC R) targeting the Borrelia specific outer surface protein (Osp) A gene in sy novial fluid for the diagnosis of Lyme arthritis, and thus permit an earlie r start to treatment. Patients and methods: Prospectively we examined the synovial fluid of 37 pa tients with the clinical diagnosis of Lyme arthritis or with other arthropa thies of known or unknown origin, searching for the presence of detectable borrelial DNA in both arms of the study. Retrospectively we examined the st ored synovial fluid from 50 patients of the Department of Rheumatology of t he University Hospital, Berne, with the clinical diagnosis of monarthritis or oligoarthritis of unknown etiology, juvenile chronic arthritis or rheuma toid arthritis. The laboratory biologist was unaware of the clinical diagno sis. Results: In the prospective study no true false positive results were found : of the 28 patients without strong clinical suspicion of Lyme arthritis 27 were PCR negative. In one case with positive PCR for borrelial DNA the dia gnosis could not be clarified, Lyme arthritis remaining a possibility. Ther efore the specificity in the prospective study was at least 96%. Borrelial DNA in the synovial fluid was found in 5 out of 9 patients with strong clin ical suspicion of Lyme arthritis. All 7 patients in this group were new, un treated cases. All the 5 PCR positive results belonged to this group, thus the "sensitivity" of the tested method was 71% in untreated cases of Lyme a rthritis. In the retrospective study we found borrelial DNA in the synovial fluid of 2 patients. These 2 patients had gonarthritis of unknown origin. Retrospectively these 2 cases could be diagnosed as Lyme arthritis. Conclusion: In cases with clinical suspicion of Lyme arthritis the PCR meth od targeting a borrelial Osp A gene fragment common to all 3 European genos pecies shows very good specificity and in untreated cases acceptable sensit ivity. Introduction of the method studied into clinical practice is justifi ed.