Reactive joint symptoms following an outbreak of Salmonella typhimurium phage type 135a

OBJECTIVE: To quantify the incidence and clinical features of reactive arthritis (ReA) developing in a cohort exposed to an outbreak of Salmonella typhimurium phage type 135a, and factors affecting host susceptibility to ReA. METHODS: A screening questionnaire was mailed to 493 patients with confirmed Salmonella infection. Musculoskeletal symptoms and extraarticular manifestations of ReA were quantified. Positive responders with joint pain were invited to participate further, with a detailed history, examination, and investigations including HLA-B27 status. RESULTS: A total of 261/461 (57%) subjects responded to the questionnaire, with 23/54 adults (43%) and 41/207 children (20%) reporting joint symptoms. Although joint pains were less common in children compared with adults, those children affected usually had eye (34%) or mucocutaneous (37%) symptoms. The incidence of ReA was 14.6%, with adults more frequently affected (24%) than children (12%). This may be an underestimate given the large proportion of children involved. Associated clinical features were similar to previous studies, with the distribution of arthritis affecting the lower limbs predominantly in an oligoarticular pattern, as were the extraarticular manifestations and enthesopathy. We found 17% of subjects were HLA-B27 positive, and 55% were still symptomatic after 6 months. CONCLUSION: In an Australian cohort study of a S. typhimurium phage type 135a outbreak, joint symptoms were common, affecting 25% of subjects. The incidence of ReA of 14.6% and the clinical features were comparable to previous studies. There was a small effect of HLA-B27 status on the development of ReA.     

Reactive arthritis and other sequelae following sporadic Salmonella typhimurium infection in British Columbia,Canada: a case control study

OBJECTIVE: To describe sequelae occurring in the 3 months after sporadic Salmonella typhimurium (ST) infection in British Columbia (BC), Canada. METHODS: We compared the incidence of sequelae to similar symptoms in controls; identified risk factors for developing sequelae; identified the incidence of reactive arthritis (ReA) as diagnosed by a rheumatologist, and assessed primary care physician diagnosis of ReA. A questionnaire was administered by telephone to cases of ST occurring in BC between December 1, 1999, and November 30, 2000; and to controls obtained from the BC provincial client registry. Cases reporting symptoms were followed up by a rheumatologist. RESULTS: Thirty-five of 66 (53%) cases reported any symptom, 17 (26%) reported joint symptoms. The Mantel-Haenszel odds ratio (weighted by sex and pediatric/adult) of a salmonella case reporting "any symptom" compared to controls was 5.42; 95% confidence interval (CI) 2.18-16.27; and reporting joint symptoms was 4.40; 95% CI: 1.25-19.53. The sex distribution of cases reporting joint symptoms was not significantly different. No medication taken during the salmonella infection was significantly different between the cases who had joint symptoms and those who did not. Four cases (2 adults, 2 children) were considered by the rheumatologist to have symptoms consistent with ReA, 2 of these had been told by a physician that their symptoms were related to their ST infection. CONCLUSION: Cases were more than 4 times more likely to report joint symptoms than controls; and despite the loss of many cases to followup, 6% of all cases were considered to have ReA.     

Reactive arthritis following an outbreak of Salmonella typhimurium phage type 193 infection

OBJECTIVES: To determine the occurrence and the clinical picture of reactive arthritis (ReA) following an outbreak of Salmonella typhimurium. METHODS: An outbreak of S typhimurium phage type DT 193 occurred in several municipalities in Finland in 1999. A questionnaire which had a specific emphasis on musculoskeletal symptoms was mailed to all 78 subjects with a positive stool culture. Based on the answers, all subjects with recent joint complaints were clinically examined or interviewed by telephone. RESULTS: Sixty three of 78 subjects (81%) returned the questionnaire. Of these 63 subjects, five (8%) fulfilled the criteria for ReA. All the five subjects with ReA were adults with oligo- or polyarthritis. The antigen HLA-B27 was positive in two of the four subjects tested. In two of five subjects with ReA, the duration of acute arthritis was over six months. Subjects who had received antimicrobial drugs developed acute musculoskeletal symptoms significantly (p=0.013) less often than those without such treatment. None of the subjects with ReA had received antimicrobial drugs before the onset of joint symptoms. CONCLUSIONS: The occurrence of ReA following an outbreak of S typhimurium was at the same level as in outbreaks due to other salmonella serotypes reported previously by us, indicating that the frequency of ReA after various outbreaks is approximately 10%. Early use of antimicrobial drugs may prevent the development of musculoskeletal symptoms.     

Frequency of triggering bacteria in patients with reactive arthritis and undifferentiated oligoarthritis and the relative importance of the tests used for diagnosis

OBJECTIVE: Reactive arthritis (ReA) triggered by Chlamydia trachomatis or enteric bacteria such as yersinia, salmonella, Campylobacter jejuni, or shigella is an important differential diagnosis in patients presenting with the clinical picture of an undifferentiated oligoarthritis (UOA). This study was undertaken to evaluate the best diagnostic approach. PATIENTS AND METHODS: 52 patients with ReA, defined by arthritis and a symptomatic preceding infection of the gut or the urogenital tract, and 74 patients with possible ReA, defined by oligoarthritis without a preceding symptomatic infection and after exclusion of other diagnoses (UOA), were studied. The following diagnostic tests were applied for the identification of the triggering bacterium: for yersinia induced ReA-stool culture, enzyme immunoassay (EIA), and Widal's agglutination test for detection of antibodies to yersinia; for salmonella or campylobacter induced ReA-stool culture, EIA for the detection of antibodies to salmonella and Campylobacter jejuni; for infections with shigella-stool culture; for infections with Chlamydia trachomatis-culture of the urogenital tract, microimmunofluorescence and immunoperoxidase assay for the detection of antibodies to Chlamydia trachomatis. RESULTS: A causative pathogen was identified in 29/52 (56%) of all patients with ReA. In 17 (52%) of the patients with enteric ReA one of the enteric bacteria was identified: salmonella in 11/33 (33%) and yersinia in 6/33 (18%). Chlamydia trachomatis was the causative pathogen in 12/19 (63%) of the patients with urogenic ReA. In patients with the clinical picture of UOA a specific triggering bacterium was also identified in 35/74 (47%) patients: yersinia in 14/74 (19%), salmonella in 9/74 (12%), and Chlamydia trachomatis in 12/74 (16%). CONCLUSIONS: Chlamydia trachomatis, yersinia, and salmonella can be identified as the causative pathogen in about 50% of patients with probable or possible ReA if the appropriate tests are used.     

Reactive arthritis following an outbreak of Campylobacter jejuni infection

OBJECTIVE: To study the occurrence and the clinical picture of musculoskeletal (MSK) complications including reactive arthritis (ReA) following an outbreak of Campylobacter jejuni. METHODS: An outbreak of C. jejuni infection occurred in 2000 in Asikkala, Finland, during which 350 exposed subjects contacted the Municipal Health Centre (MHC). All primary care physicians in the MHC were advised to refer patients with acute MSK complications to the Rheumatism Foundation Hospital (RFH) for a specialist clinical examination, which was performed 相似文献   

Reactive arthritis after an outbreak of Yersinia pseudotuberculosis serotype O:3 infection

OBJECTIVE: To determine the occurrence and clinical characteristics of reactive arthritis (ReA) after an outbreak of Yersinia pseudotuberculosis serotype O:3 infection. METHODS: From 15 October to 6 November 1998, a widespread outbreak of Y pseudotuberculosis serotype O:3 occurred in Finland. A questionnaire on musculoskeletal symptoms was mailed to 38 patients with infection confirmed by culture. All patients who reported joint symptoms were interviewed by phone and their medical records of outpatient visits or hospital admission because of recent joint symptoms were reviewed. RESULTS: Thirty three of 38 (87%) patients returned the questionnaire. Reactive musculoskeletal symptoms were reported by 5/33 (15%): four patients (12%) fulfilled the criteria for ReA and one additional patient had reactive enthesopathy. The patients with ReA were adults (age range 40-47 years), whereas the patient with reactive enthesopathy was a 14 year old boy. In all patients with ReA, the arthritis was polyarticular. In addition to peripheral arthritis, other musculoskeletal symptoms included sacroiliitis (one patient), pain in Achilles tendon (one patient), and heel pain (two patients). HLA-B27 was positive in all the three patients tested. In three of four patients with ReA, the duration of acute arthritis was over six months. CONCLUSION: Y pseudotuberculosis serotype O:3 infection is frequently associated with ReA and the clinical picture is severe.     

Reactive arthritis

Reactive arthritis (ReA) can be defined as the development of sterile inflammatory arthritis as a sequel to remote infection, often in the gastrointestinal or urogenital tract. Although no generally agreed-upon diagnostic criteria exist, the diagnosis is mainly clinical, and based on acute oligoarticular arthritis of larger joints developing within 2-4 weeks of the preceding infection. According to population-based studies, the annual incidence of ReA is 0.6-27/100,000. In addition to the typical clinical picture, the diagnosis of ReA relies on the diagnosis of the triggering infection. Human leucocyte antigen (HLA)-B27 should not be used as a diagnostic tool for a diagnosis of acute ReA. In the case of established ReA, prolonged treatment of Chlamydia-induced ReA may be of benefit, not only in the case of acute ReA but also in those with chronic ReA or spondylarthropathy with evidence of persisting chlamydia antigens in the body. In other forms of ReA, there is no confirmed evidence in favour of antibiotic therapy to shorten the duration of acute arthritis. The outcome and prognosis of ReA are best known for enteric ReA, whereas studies dealing with the long-term outcome of ReA attributable to Chlamydia trachomatis are lacking.     

Campylobacter reactive arthritis: a systematic review

OBJECTIVE: To review the literature on the epidemiology of Campylobacter-associated reactive arthritis (ReA). METHODS: A Medline (PubMed) search identified studies from 1966 to 2006 that investigated the epidemiology of Campylobacter-associated ReA. Search terms included: "reactive arthritis," "spondyloarthropathy," "Reiter's syndrome," "gastroenteritis," "diarrhea," "epidemiology," "incidence," "prevalence," and "Campylobacter." RESULTS: The literature available to date suggests that the incidence of Campylobacter ReA may occur in 1 to 5% of those infected. The annual incidence of ReA after Campylobacter or Shigella may be 4.3 and 1.3, respectively, per 100,000. The duration of acute ReA varies considerably among reports, and the incidence and impact of chronic ReA from Campylobacter infection is virtually unknown. CONCLUSIONS: Campylobacter-associated ReA incidence and prevalence varies widely among reviews due to case ascertainment differences, exposure differences, lack of diagnostic criteria for ReA, and perhaps genetics and ages of exposed individuals. At the population level it may not be associated with HLA-B27, and inflammatory back involvement is uncommon. Follow-up for long-term sequelae is largely unknown. Five percent of Campylobacter ReA may be chronic or relapsing (with respect to musculoskeletal symptoms).     

Campylobacter-triggered reactive arthritis: a population-based study

OBJECTIVE: To study the incidence and clinical picture of Campylobacter-associated reactive arthritis (ReA) and other reactive musculoskeletal symptoms in the population. METHODS: A questionnaire on enteric and extraintestinal, including specifically musculoskeletal, symptoms was sent to 870 consecutive patients with Campylobacter-positive stool culture and 1440 matched controls. Analysis of self-reported musculoskeletal symptoms with clinical examination was performed. RESULTS: Forty-five of the patients (7%) had ReA and eight (1%) had reactive tendinitis, enthesopathy or bursitis. No child had ReA. The arthritis was oligo- or polyarticular, and, in most cases, mild. HLA-B27 was positive in 14% of ReA patients. Of the 45 ReA patients, 37 had C. jejuni and 8 had C. coli infection. No controls had ReA. CONCLUSION: ReA is common following Campylobacter infection, with an annual incidence of 4.3 per 100000. At the population level, acute ReA is mild, more frequent in adults, and not associated with HLA-B27. Besides C. jejuni, C. coli can trigger ReA.     

Reactive arthritis attributable to Shigella infection: a clinical and epidemiological nationwide study

OBJECTIVES: To study the incidence and clinical picture of Shigella associated reactive arthritis (ReA) and the arthritogenicity of various Shigella species in the population. METHODS: A questionnaire on enteric and extraintestinal, especially musculoskeletal, symptoms was sent to 278 consecutive patients with Shigella positive stool culture and to 597 controls. Analysis of self reported musculoskeletal symptoms was supplemented with clinical examination of those subjects with recent symptoms. RESULTS: Of the patients, 14/211 (7%) had ReA, and a further 4/211 (2%) other reactive musculoskeletal symptoms (tendonitis, enthesopathy, or bursitis). Of the 14 patients with ReA, all adults, 10 had S sonnei, three S flexneri, and one S dysenteriae infection. HLA-B27 was positive in 36% of the patients with ReA. One control subject had ReA. In the patients with Shigella infection, the odds ratio for developing ReA was 16.2 (95% confidence interval 2.1 to 123.9), p = 0.001. CONCLUSIONS: ReA occurred in 7% of patients after Shigella infection, with an annual incidence of 1.3/1 000 000 in Finland. Besides S flexneri, S sonnei and S dysenteriae can also trigger ReA.     

HLA-B27 expression and reactive arthritis susceptibility in two patient cohorts infected with Salmonella Typhimurium

Background: Reactive arthritis (ReA) is an inflammatory arthritis triggered by certain gastrointestinal and genitourinary infections. Single source outbreaks of triggering infections provide an opportunity to elucidate host susceptibility factors in this disease. Aim: To determine the role of Major Histocompatibility Complex (MHC) Class I alleles in ReA susceptibility after two large single source outbreaks of Salmonella Typhimurium gastroenteritis. Methods: A questionnaire screening for features of ReA and a request for HLA class I typing were sent to all patients affected by two single source outbreaks of S. Typhimurium gastroenteritis. Individuals with arthritis of recent onset were interviewed, examined and diagnostic criteria for ReA applied. Results: Nineteen cases of reactive arthritis, 11 female, were diagnosed in the 424 respondents with S. Typhimurium gastroenteritis from both outbreaks. Clinical features of the arthritis were similar to those described after other large single source outbreaks of Salmonella infection. HLA‐B27 was expressed by only two of the 19 ReA patients and therefore did not predict susceptibility to this form of arthritis. Caucasians were, however, more likely to develop reactive arthritis than Asians. Conclusions: In this study, susceptibility to ReA was not increased in HLA‐B27 positive individuals or males but was greater in those of Caucasian descent.     

Frequency of recent parvovirus infection in patients examined for acute reactive arthritis. A study with combinatorial parvovirus serodiagnostics

OBJECTIVE: To determine the causative role of human parvovirus B19 as a preceding infection in patients examined for acute reactive arthritis (ReA). METHODS: Sixty adult patients with acute arthritis were screened for evidence of triggering infections. In all patients, cultures of stool specimens and of Chlamydia trachomatis in urethra/cervix, and/or bacterial serology were studied. The timing of primary infection of human parvovirus B19 was determined by measurement in serum of VP2-IgM, VP2-IgG, epitope-type specifity of VP2-IgG, and avidity of VP1-IgG. RESULTS: Median time from onset of joint symptoms to the rheumatological consultation was five weeks (range 1-62). Of the 60 patients, 35 fulfilled the diagnostic criteria for ReA; in the remaining, the diagnosis was unspecified arthritis (UA). Thirty-six patients had antibodies for the B19 virus. Occurrence of these antibodies did not differ significantly between ReA and UA groups (P = 0.61). Of these 36 patients, 34 had a pre-existing immunity to the B19 virus. Of the two other patients, one had rash and self-limiting polyarthritis with serological evidence of B19 primary infection, and the other had arthritis of the lower extremities with serological evidence of a convalescence period after the B19 primary infection. The latter patient also had antibodies to Yersinia, with a clinical picture typical for ReA. CONCLUSION: In patients examined for acute ReA, the frequency of recent B19 virus infection was 3.3% (2 out of 60). The diagnostic utility of the presented methodology, by using a single serum sample, was evident.     

Update zur reaktiven Arthritis

The following review summarizes the evidence on reactive arthritis (ReA), focussing on the latest relevant work on epidemiology, diagnosis, pathogenesis, and treatment. ReA is a joint inflammation that develops after a primary, extra-articular infection; the infection often involves the urogenital or gastrointestinal system, and less frequently the respiratory tract. The microbial agent causing the primary infection and triggering the arthritis cannot be cultured from the synovial compartment by standard methods; however, bacterial antigens or nucleic acids originating from Chlamydia trachomatis and other microbes can be detected within joint material. ReA occurs worldwide with a prevalence of 40/100,000 and an incidence of 5/100,000. The arthritis develops within days or weeks after the primary infection and usually affects the lower extremities. A dactylitis of the toes is highly typical, while axial or extra-articular manifestations are less common. The disease subsides in many cases within weeks or months, however relapses can occur and chronic forms are described in 30?% of patients.     

The value of specific antibody detection and culture in the diagnosis of reactive arthritis

Summary Joint inflammation, predominantly of the lower limbs, occurring some weeks after urogenital or gastrointestinal infection is classified as reactive arthritis (ReA) but there is no general agreement on diagnostic criteria, especially if the preceding infections are asymptomatic. The same is true for Lyme disease (LD) which is caused by Borrelia burgdorferi (BB). Determination of antibody titre or culture of urethral swabs and stools are often used as diagnostic tools. We examined 4 groups of patients: one with undifferentiated arthritis (Group I, n=55), one with well-defined rheumatic diseases other than ReA (n=43, Group II), one group without joint disease (n=50, Group III) and one with ReA or LD (n=7). Specific antibacterial antibody titres in serum were measured in all patients; stool and urethral cultures were performed in all groups except the last. A calculation of positive predictive value (PPV) was done for each test. Evidence of present or previous infection with the microbes Chlamydia trachomatis (CT), Mycoplasma urethritidis (MU), Yersinia enterocolitica (YE) and BB were found in all groups. In Group I, Group II and Group III respectively, positive serological results were found for CT IgA (20%, 31%, 16%) and IgG (49%, 51%, 34%), YE (7%, 6%, 0%) and BB (17%, 2%, 10%). Positive cultures were found in Group I and Group II respectively for CT (28%, 29%) and MU (14%, 17%). Therefore no test had a significant positive predictive value for ReA in the general population and even in the rheumatology clinic the PPV for most tests was low. We conclude that these methods are of little value in the diagnosis of reactive arthritis when the preceding infection is asymptomatic.     

Chlamydia pneumoniae--a new causative agent of reactive arthritis and undifferentiated oligoarthritis.

OBJECTIVE--To examine whether reactive arthritis (ReA) known to occur after a urogenital infection with Chlamydia trachomatis can also follow an infection with Chlamydia pneumoniae, a recently described species of Chlamydiae that is a common cause of respiratory tract infections. METHODS--Specific antibodies (microimmunofluorescence test) and lymphocyte proliferation to C trachomatis and C pneumoniae in paired samples of peripheral blood and synovial fluid were investigated in 70 patients with either reactive arthritis (ReA) or undifferentiated oligoarthritis (UOA). RESULTS--Five patients with acute ReA after an infection with C pneumoniae are reported. Three had a symptomatic preceding upper respiratory tract infection and two had no such symptoms. In all patients a C pneumoniae-specific lymphocyte proliferation in synovial fluid and a high specific antibody titre suggesting an acute infection was found. CONCLUSION--C pneumoniae needs to be considered a new important cause of reactive arthritis.     

Total incidence and distribution of inflammatory joint diseases in a defined population: results from the Kuopio 2000 arthritis survey

OBJECTIVE: To study the incidence of inflammatory joint diseases in a defined population in Finland. METHODS: We collected data for the year 2000 on a population of 87,000 inhabitants of Kuopio, Finland, of whom 20% were < 16 years of age. Information about the study was given through a local newspaper, and subjects attended one health center and 2 local hospitals for study. Inclusion criteria were that subjects have at least one peripheral joint with synovitis or signs of inflammation in sacroiliac, glenohumeral, or hip joints on the first visit. Incidence rates were calculated according to the diagnosis on the first visit, except for children, for whom diagnoses were established after 3 months' followup. RESULTS: A total of 188 adult incident cases (138 women, 50 men) and 11 children (8 girls, 3 boys) satisfied the inclusion criteria. The incidence of all arthritides was 230/100,000 (95% confidence interval 198.9-263.9) for the whole population; 271/100,000 (95% CI 233.7-312.7) for adults and 64/100,000 (95% CI 31.7-113.8) for children. Among adults the annual incidence of rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis (ReA), other spondyloarthropathies (SpA), connective tissue disease (CTD), crystalline arthritis, viral arthritis, and undifferentiated arthritis were 36, 7, 23, 10, 13, 9, 19, 7, and 149/100,000, respectively. The mean age at diagnosis was 49.4 +/- 16.3 years for all cases of arthritis among adults, about the same for both women and men. The mean age at diagnosis was 59.7 years in RA, 31.5 years in AS, 48.7 years in PsA, 38.0 years in ReA, 36.5 years in other SpA, 36.1 years in CTD, 65.0 years in crystalline arthritis, 53.3 years in viral arthritis, and 48.3 years in undifferentiated arthritis. Four of 11 children had juvenile idiopathic arthritis (JIA). The incidence of JIA was 23/100,000 in the population < 16 years of age. Of the remaining cases, 3 children had antibodies against Sindbis (Pogosta) virus and 4 had a transient monoarthritis. CONCLUSION: The overall incidence of arthritides among adults was slightly higher than previously reported from Finland. The incidence rates in the child population are in agreement with previous figures. These data are useful in planning the provision of health care.     

Cutaneous vasculitis and reactive arthritis following respiratory infection due to Chlamydia pneumoniae: report of a case

Unlike Chlamydia trachomatis and C. psittaci, the association of C. pneumoniae infection with immunological complications, such as reactive arthritis (ReA) or erythema nodosum (EN) has been rarely reported. Here we present the case history of a patient with C. pneumoniae community acquired pneumonia (CAP) who subsequently developed a ReA and a cutaneous vasculitis. A 45-year-old HLA B27 negative male developed an asymmetric and additive arthritis and a cutaneous leukocytoclastic vasculitis with IgM and complement papillary deposition along hypodermic vessel walls about three weeks after the onset of respiratory symptoms. The diagnosis of chronic Chlamydia pneumoniae infection was based on serology and PCR. Cultural and serological investigations for other infectious agents commonly involved in ReA were negative. This is the first report on the occurrence of two immune-based complications, associated to Chlamydia pneumoniae infection. Therefore, since this infection is very common in our population, although often asymptomatic, should be systematically considered as a common causative agent of ReA and of vasculitis.     

Infections preceding early arthritis in southern Sweden: a prospective population-based study

OBJECTIVE: To detect evidence of infections preceding early arthritis in Southern Sweden and to compare the clinical outcome of remission during a 6-month followup for patients with and without signs of prior infection. METHODS: Adult patients with arthritis of less than 3 months' duration were referred from primary health care centers to rheumatologists. All patients were systematically screened for infections caused by Salmonella typhimurium and Salmonella enteritidis, Yersinia enterocolitica, Campylobacter jejuni, Borrelia burgdorferi, Chlamydia trachomatis, Chlamydia pneumoniae, and parvovirus B19. RESULTS: Seventy-one patients were included in this study. Twenty-seven (38%) patients had reactive arthritis (ReA), 17 (24%) undifferentiated arthritis, 15 (21%) rheumatoid arthritis (RA), 4 (6%) psoriatic arthritis, and the rest (11%) other diagnoses. Of all the patients, 45% had evidence of a recent infection preceding the arthritis, as indicated by laboratory tests and/or disease history. C. jejuni dominated the ReA group. The occurrence of recent C. trachomatis, B. burgdorferi, C. pneumoniae, and parvovirus B19 infections was low. Overall, 58% of the patients went into remission during the 6-month followup. Of the patients with a preceding infection, 69% went into remission as compared to 38% of the patients without a preceding infection (p = 0.011). Thirty-three percent of the patients with RA were in remission after 6 months. CONCLUSION: In this population-based cohort, 45% of the patients presenting with a new-onset arthritis had had a prior infection. Campylobacter ReA dominated the ReA group. There were only a few cases preceded by infections by C. trachomatis, B. burgdorferi, C. pneumoniae, and parvovirus B19 infections. Remission during the first 6 months was especially frequent in the group of patients with a prior infection, but the remission rate was relatively high even for arthritis without prior infection.     

On the difficulties of establishing a consensus on the definition of and diagnostic investigations for reactive arthritis. Results and discussion of a questionnaire prepared for the 4th International Workshop on Reactive Arthritis, Berlin, Germany, July 3-6, 1999

OBJECTIVE: There is no agreement on how to classify and diagnose reactive arthritis (ReA) and it is also unclear what kind of specific clinical and laboratory investigations are appropriate. We define relevant points of agreement and identify points of disagreement among an international group of experts in the field. METHODS: Prior to the 4th International Workshop on Reactive Arthritis, Berlin, July 1999, we sent questionnaires to 42 experts identified by personal knowledge and recent publications. RESULTS: The response rate was 81% (n = 34). There was agreement on the nomenclature and recommendation to use the term "reactive arthritis" only if the clinical picture and the microbes involved are HLA-B27 and spondyloarthropathy (SpA) associated, whereas the term "infection related arthritis" is used for all other arthritides related to or associated with infections. A differentiation between acute and chronic ReA with a cutoff of 6 months is recommended. The history of a preceding symptomatic infection is thought to be most relevant for a diagnosis of ReA. The minimal interval between preceding symptoms and arthritis is proposed to be 1-7 days, maximally 4 weeks. The joint pattern in ReA is asymmetrical, with predominance of the lower limbs. SpA related symptoms may contribute to the diagnosis. A search for chlamydia in urine/urethra/cervix is recommended, while in the case of diarrhea enterobacteria should be searched for in stool and antibodies against them in serum. There were also areas of disagreement, such as: Is arthritis essential for the diagnosis of ReA?, Is it oligoarthritis or any arthritis?, What are the role and value of polymerase chain reaction investigation?, The role and value of serology?, Is the diagnostic sensitivity of microbiological tests for ReA increased by HLA-B27 determination? CONCLUSION: The points of agreement will support better communication in this area, and clarification of the disagreements will lead to further studies and discussion.