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Microbes reach the synovial cavity either directly during bacteraemia or by transport within lymphoid cells or monocytes. This may stimulate the immune system excessively, triggering arthritis. Some forms of ReA correspond to slow infectious arthritis due to the persistence of microbes and some to an infection triggered arthritis linked to an extra-articular site of infection.

Resume Propos. – La borreliose de Lyme est une infection systemique due a un spirochete, Borrelia burgdorferi. Dans les zones dˈendemie europeennes, en particulier dans le Nord-Est de la France, les manifestations articulaires sont, apres les atteintes neurologiques, le mode de revelation le plus frequent des formes non cutanees de la maladie. Parmi les especes de Borrelia pathogenes, Borrelia burgdorferi sensu stricto est la plus frequemment identifiee au cours de arthrites de Lyme, mais dˈautres especes peuvent etre en cause. Actualites et points forts. – Habituellement, le diagnostic dˈarthrite de Lyme est surtout fonde sur la conjonction des elements cliniques et des resultats dˈune serologie specifique. Dans les formes atypiques, la recherche de fragments du genome bacterien intra-articulaire par PCR peut etre un argument diagnostique. Alors que les mecanismes impliques dans les phases aigues de lˈarthrite de Lyme commencent a etre mieux connues, la physiopathologie des arthrites chroniques, qui concerne plus de 10 % des patients, reste inexpliquee. Deux theories sont actuellement evoquees pour expliquer lˈevolution prolongee des atteintes articulaires : une persistance de Borrelia burgdorferi, qui echappe au systeme immunitaire synovial et/ou un mecanisme auto-immun lie a un mimetisme moleculaire original. Le traitement antibiotique est bien codifie dans les formes articulaires aigues, mais il nˈest pas adapte sous la forme actuelle dans les arthrites chroniques ou les manifestations tardives de type fibromyalgique couramment appelees post Lyme disease. Perspectives et projets. – Pour prevenir la maladie, le vaccin actuellement commercialise aux Etats-Unis nˈoffre pas une protection absolue et il nˈest pas utilisable en Europe en raison de la diversite des especes pathogenes presentes dans nos regions. Les progres realises dans la comprehension des mecanismes pathogeniques de la maladie permettra peut-etre, a moyen terme, de proposer de nouvelles options preventives et therapeutiques plus adaptees.

Since very little is known about the clinical expression of Lyme borreliosis in Western Europe, a 3-year prospective study was conducted that included all patients seen for suspected Lyme borreliosis at the Strasbourg University Hospital in northeastern France. The diagnosis of Lyme borreliosis was made on the basis of the presence of erythema migrans or on the basis of another suggestive clinical manifestation and laboratory confirmation. A total of 132 patients, 70 women and 62 men, mean age 54 years, had Lyme borreliosis according to these criteria. Within this study group, 77% of the patients were regularly exposed to tick bites and 64% could remember one. Erythema migrans, the most frequent clinical manifestation, occurred in 60% of the patients and was the only sign of Lyme borreliosis in 40%. Lymphocytoma and acrodermatitis chronica atrophicans were rare (1 and 3 patients, respectively). Nervous system involvement (mainly radiculoneuropathy), the second most common clinical manifestation, was found in 40% of the patients and was the only sign of Lyme borreliosis in 22%. Musculoskeletal involvement was present in 26% of the patients and was an isolated finding in 14%. During the study period, no patient was diagnosed with Lyme carditis. There was serological evidence of Lyme borreliosis in 75% of the cases and direct evidence of borrelial infection in 10 (7.5%). The results show that the clinical expression of Lyme borreliosis in northeastern France is similar to that in other European countries but different from that in North America.

Since Lyme arthritis was first described in the United States, it has now been reported in many countries of Europe. However, very few strains of the causative bacterium, Borrelia burgdorferi , have been isolated from synovial samples. For this reason, different molecular direct typing methods were developed recently to assess which species could be involved in Lyme arthritis in Europe. We developed a simple oligonucleotide typing method with PCR fragments from the flagellin gene of B. burgdorferi sensu lato, which is able to differentiate seven different Borrelia species. Among 10 consecutive PCR-positive patients with Lyme arthritis from the northeastern France, two species were identified in synovial samples: B. burgdorferi sensu stricto in 9 cases and B. garinii in 1 case. Conversely, all B. burgdorferi sensu lato species detected in 10 consecutive PCR-positive biopsies from a second set of patients with erythema migrans from the same geographical area were identified as either B. afzelii or B. garinii ( P < 0.001). These results indicate that B. burgdorferi sensu stricto is the principal but not the only Borrelia species involved in Lyme arthritis in northeastern France.

A one-step reverse transcriptase PCR (RT-PCR) method for detection of Borrelia burgdorferi mRNA in infected C3H mice is described. This simple procedure, less prone to nucleic acid cross-contamination than the standard method, was found to be 10-fold more sensitive than a classical two-step RT-PCR assay. By using one-step RT-PCR, flagellin mRNAs were detected in synovial and heart tissues from all seven infected mice tested.

Lyme borreliosis is a multisystemic infection caused by the spirochaete Borrelia burgdorferi. In European endemic areas like northeast France, articular manifestations are, after neuroborreliosis, the most frequent extra-cutaneous features observed. Among the pathogenic species of Borrelia, Borrelia burgdorferi sensu stricto is the most frequently identified during Lyme arthritis, but others species also seem to be involved.The diagnosis of Lyme arthritis is usually based on combined clinical data and serological laboratory tests. In atypical forms, detection of bacterial DNA could be useful. While mechanisms involved in acute Lyme arthritis are beginning to be better understood, the pathogenesis of chronic arthritis, which concerns about 10% of the patients, remains unknown. Two hypotheses are proposed to explain the prolonged evolution of the articular disease: a chronic persistence of Borrelia burgdorferi, which evades the host immune system within the joint and/or an autoimmune mechanism by molecular mimicry. The antibiotic therapy is codified in acute arthritis, but is not really adapted in chronic Lyme arthritis or post-Lyme syndrome.To prevent the disease, the vaccine available in the United States does not offer complete protection and is not useful in Europe since the species heterogeneity is important for the outer surface protein A. A better understanding of Lyme disease pathogenesis can subsequently lead to new therapeutic or preventive approaches.

Background Procalcitonin (PCT), the calcitonin peptide precursor, is a new specific marker of severe bacterial and fungal infections. PCT is not or slightly elevated in others inflammatory diseases. PCT measurements could help to differentiate bacterial arthritis to other forms of acute arthritis. Objectives To determine the interest of serum and synovial PCTfor the diagnosis of acute bacterial arthritis. Methods A one year prospective study (RR study group): sera and synovial fluid from 32 adults with acute arthritis were immediately frozen (-20°C) before treatment. for all patients, the diagnosis was confirmed by specific synovial analysis. PCT (N Results Results are expressed in median and range. Values are compared between septic group and crystal or rheumatoid group by Mann-Whitney test: **p Conclusion These results show that plasma PCT levels are higher in patients with septic arthritis, but PCT sensitivity remains unsufficient. However, in case of bacterial arthritis, PCT in association with CRP, could be of great interest for clinicians, as its increase is in favour of a bacterial origin. PCT is not present in all biological fluids. If synovial PCT does not seem to be helpful in clinical diagnosis, this study is, to our knowledge, the first to demonstrate PCT existence in synovial fluid.

Background The Ku autoantigen is a DNA binding factor consisting of 70 and 80 kDa protein which form a heterodimer involved in repair of ds DNA breaks. Since the original description of anti-Ku antibody in patients with polymyositis-scleroderma overlap syndrome, this antibody has been showed to be associated with several autoimmune diseases. Objectives To describe clinical features of 8 patients with anti-KU antibody. Methods Results Conclusion anti-Ku antibody is not specific of a connective tissu disease and can also be observed in patients without any autoimmune disease (n°7). In addition to previous described association, anti-Ku antibody can also be present in Wegener granulomatosis and idiopathic Raynaud’s phenomen. Two of our patients had an evaluative cancer (n°5 and 8) and one (n°7) presented a stomach neoplasm 3 years before the detection of anti-Ku antibody. This finding needs further investigations to assess if anti-Ku antibody can be associated with or predictive of a neoplasm.

Lyme arthritis is caused in Europe by three main pathogenic species of Borrelia burgdorferi sensu lato: Borrelia burgdorferi sensu stricto, Borrelia garinii, and Borrelia afzelii. Because few synovial samples have yet been analysed by species-specific DNA amplification methods, further studies are needed to define the spectra of clinical manifestations associated with these different species. Two cases of treatment resistant Lyme arthritis are reported here, in which DNA amplification of the flagellin gene followed by dot-blot hybridisation in the synovial fluid identified B garinii as the causative agent. Clinical and biological data did not differ from the usual descriptions of Lyme arthritis, but as the recently reported molecular mimicry between OspA and hLFA1 is not applicable to B garinii, the pathogenesis of the present cases remains unclear. Future studies should aim at assessing the role of B garinii in European Lyme arthritis and its possible pathogenic and therapeutic consequences.