Development of an experimental model of septic knee arthritis in rats through intra-articular inoculation of Staphylococcus aureus.

Haematogenous models of septic arthritis have some inherent disadvantages, such as the manifestation of arthritis relies on chance, the size of the inoculum is unknown and the number of animals to be studied cannot be reduced because the animals cannot serve as their own controls. This study aimed to develop a rat model of knee septic arthritis by injecting a known inoculum of Staphylococcus aureus into the joint. The left knees of 27 Sprague Dawley rats were injected with four different inoculum concentrations of a sensitive strain of S. aureus (30,000 colony-forming units (CFUs), n = 3; 18,550 CFUs, n = 6; 15,500 CFUs, n = 9; and 7700 CFUs, n = 9); the right knees served as controls. Clinical, microbiological and histological variables were assessed two and seven days later. The main criterion for diagnosing septic arthritis was a positive culture of synovial fluid. The rate of microbiologically confirmed septic arthritis was high for all inoculum concentrations (3/3, 6/6, 8/9 and 7/9, respectively), and the rate of bacteraemia was also high. Animal welfare was better for the two lowest inoculum concentrations. No animal reached the pre-established humane end points. Overall, the third inoculum was considered the most suitable. Thus, acute septic arthritis can be caused in rats by inoculating 15,000 CFUs of an ATCC strain of S. aureus directly into the knee joint. Overall, the model seems to be useful for studying the effectiveness of drugs for the treatment of acute septic arthritis.

Pathogenesis of restricted movements in trichinellosis: an experimental study.

Trichinellosis is a zoonosis acquired by the ingestion of insufficiently cooked pork meat containing the encapsulated larvae of Trichinella spiralis. Trichinellosis is presented with myalgia which affects various muscle groups; its intensity is usually related to the severity of the disease and may cause restriction of joint movement. However, joint pain in the course of trichinellosis could not be explained entirely by myositis. This study investigated the other possible causes of restricted movements of joints in animal model. We found that the histopathological changes in the joints of T. spiralis infected rats were in the form of inflammatory cellular infiltrates and ulceration in the synovial membrane with degeneration and ulceration of the articular cartilage. Immunohistochemical examination of the joints revealed the presence of T. spiralis local antigen or immune complex deposited in the synovial membrane. Leukocytosis and eosinophilia were observed throughout the experimental period but eosinophil level declined slowly but still elevated. In conclusion, the restricted movements during the course of trichinellosis seem to be not only due to direct invasion of muscles by the encapsulated T. spiralis larvae but also due to immune complex deposition in the joints.

Intraarticular Dirofilaria immitis microfilariae in two dogs.

Dirofilaria immitis microfilariae were found in the synovial fluid of two dogs. One dog had clinical and cytological evidence of polyarthritis at the time of presentation. The second dog presented with severe effusion in a single joint and was later diagnosed with synovial sarcoma of the affected joint. These patients were not protected with heartworm prophylaxis and lived in heartworm endemic areas. Though there is documentation of D. immitis microfilaria in the synovial fluid of several clinically normal research dogs with cytologically normal synovial fluid, to our knowledge these are the first documented cases of intraarticular microfilaria in a dog with cytologically confirmed polyarthritis. Based on these unique cases, D. immitis infection should be considered a differential diagnosis in patients with polyarthropathies. Interpretive caution must be used when intraarticular microfilaria are present, as concurrent etiologies may also be present.

Primary hydatid disease of sacrum affecting the sacroiliac joint: a case report.

STUDY DESIGN: A case report of hydatid disease of the spine. OBJECTIVE: To describe an unusual case of hydatid disease of the sacrum affecting the sacroiliac joint and to discuss imaging, differential diagnosis, and treatment. SUMMARY OF BACKGROUND DATA: Hydatidosis or echinococcosis affecting the spine is rare and has a characteristic geographic distribution. Signs of sacroiliac joint involvement and accompanying neurologic deficits cause difficulties in differential diagnosis of this rare condition. METHODS: A case of 38-year-old female patient with low back pain and sciatica was presented. RESULTS: Plain radiographs, computed tomography, and magnetic resonance imaging scans revealed destructive expansive lesion located on the right sacrum and extended through the right sacroiliac joint. Surgical enucleation of the cysts was performed together with mebendazole treatment and histopathologic examination confirmed hydatidosis. CONCLUSION: This unusual disease should be kept in mind in the differential diagnosis of sacroiliac pain and sciatica, especially in endemic areas.

Reactive arthritis associated with prolonged cryptosporidial infection.

In contrast to arthritic disease caused by different bacterial agents, reactive arthritis due to parasitic infection is rare. We report on an 8-year-old immunocompetent boy with a symptomatic intestinal cryptosporidiosis over a 13-months period. The protozoan infestation was accompanied by arthritic symptoms involving several joints at different times (migratory arthritis). Symptoms resolved spontaneously after 20 months in parallel with stool samples negative for cryptosporidia.

Extralymphatic disease due to bancroftian filariasis.

Infection with Wuchereria bancrofti, Brugia malayi, or B. timori not only affects the structure and function of lymphatic vessels but is also associated with extralymphatic pathology and disease. Because it is now possible to detect living adult worms by ultrasonography, much emphasis is placed on lymphatic pathology. However, the finding of renal damage in asymptomatic microfilaremic carriers has led to increased recognition of the importance of extralymphatic clinical manifestation in bancroftian filariasis. The authors present a number of clinical syndromes that may be manifestations of extralymphatic filarial disease and discuss possible mechanisms that cause these conditions. The main purpose of this paper is to raise the awareness of students and physicians of the prevalence and the importance of extralymphatic disease in bancroftian filariasis so that it is diagnosed and treated properly and also to alert for the need of additional research in this area.

Study of interleukin-2 receptor in schistosomiasis mansoni and its analogous changes in collagen diseases and schistosomal arthropathy.

An enzyme linked immunosorbent assay was used to quantify soluble interleukin-2 receptor (sIL-2R) in the serum of patients with different stages of S. mansoni infection, rheumatoid arthritis, systemic lupus erythematosus (SLE) and schistosomal arthropathy. The results demonstrated significant higher level of sIL-2R in different patient groups compared to the control group. The highest level of sIL-2R was recorded in hepatosplenic schistosomiasis complicated with ascites. The difference was statistically significant compared to other groups. There was no significant difference in sIL-2R regarding rheumatoid arthritis and SLE. Schistosomal arthropathy group showed significant higher level of sIL-2R compared to rheumatoid arthritis, SLE and early S. mansoni infection while the difference was insignificant compared to hepatosplenic schistosomiasis without ascites.

[Blastocystis hominis as a rare arthritogenic pathogen. A case report]. / Blastocystis hominis als seltener arthritogener Erreger. Ein Fallbericht.

Blastocysts hominis, a protozoon considered to be a nonpathogen intestinal commensal, is now discussed to be a cause of intestinal infection under certain circumstances, e.g., immunosuppression. There are two published cases of Blastocysts infection complicated by arthritis which was classified as "reactive" in one case, "infectious" in the other. We report a third case: A 46-year-old female patient developed a chronic diarrhea and oligoarthritis some days after returning from a trip to Senegal. Arthritis was refractory against treatment with NSAID and corticosteroids. Finally, a 3-week course of treatment with metronidazole resulted in a complete remission of arthritis, gastrointestinal symptoms, and inflammation signs (ESR, CRP). The course in our case, as well as the detection of Blastocysts hominis in synovial fluid in another case, implicate an infectious rather than a reactive etiology of arthritis.

Arthritis in children: an occult manifestation of Bancroftian filariasis.

A form of unexplained arthritis, not attributable to known causes, seen in children (0-14 yrs) in this endemic zone of Bancroftian filariasis was investigated for its association with filariasis. Nineteen cases of undiagnosed arthritis were screened for filarial IgG antibodies to Wuchereria by Stick Enzyme Linked Immunosorbent Assay (ELISA). All had large joint involvement, the commonest joint affected being the knee joint. Involvement was monoarticular in 10 and binarticular in 9. Joint pain was present in 18 and effusion in 12. Five patients had recurrent episodes. Sixteen (84.2%) showed filarial antibodies of which only one (5.3%) was microfilaraemic. Patients with classical filariasis (16), disease controls (10), endemic normals (15) and non-endemic normals (10) were also subjected to ELISA to ascertain the sensitivity and specificity of the technique. Fifteen (93.8%) cases of classical filariasis and 1 (6.7%) of endemic normal were antibody positive, whereas none of disease controls and non-endemic normals had filarial antibodies. Nine cases of filarial arthritis reviewed after a course of Diethylcarbamazine showed satisfactory response to treatment.

Synovial schistosomiasis of the hip.

Schistosomiasis is a common parasitic infestation in Egypt. We describe the case of a 24-year-old Egyptian man who presented with the signs of acute septic arthritis of the hip and in whom biopsy subsequently revealed schistosome ova in the synovium.

Isolation of Entamoeba histolytica from arthritic knee joint.

Amoebae were isolated from an arthritic knee of a male patient. The organisms grew in Egg Yolk Infusion medium, and in Diamond's Biosate Iron-Serum-33 medium, which contained Trypanosoma cruzi, and were identified microscopically as Entamoeba histolytica. Furthermore, amoebae-like organisms in aspirate and cultures were immunocytochemically identified using monoclonal antibodies against E. histolytica. On the basis of the morphologic and immunologic observations, it was concluded that the knee lesion was caused by infection with E. hystolytica. The knee lesion resolved following treatment with metronidazole. This case is the first report of an amoebic infection of the knee joint.

Arthritis due to tuberculosis, fungal infections, and parasites.

Tuberculous, fungal, and parasitic infections infect millions of people throughout the world. While other problems usually overshadow their rheumatologic manifestations, nearly all these infections can involve bone or joints and may on occasion present with rheumatologic symptoms. The classic model of these diseases presenting as chronic monoarticular arthritis is still generally valid but other presentations, such as tenosynovitis with atypical mycobacterial infections, erythema nodosum with leprosy, coccidioidomycosis and histoplasmosis, and reactive arthritis with schistosomiasis and helminthic infections, are now well established. The most dramatic change in the epidemiology of tuberculous infections in recent years is the increasing incidence in patients with the acquired immunodeficiency syndrome (AIDS). Mycobacterium avium complex infections in particular have increased dramatically and are a major problem in the later stages of AIDS. Reports of septic arthritis and tenosynovitis due to M. avium are likely to increase over the next few years.

Infective arthritis due to Blastocystis hominis

A patient with rheumatoid arthritis taking prednisone developed Blastocystis hominis acute diarrhoea, which was associated with increased inflammation and effusion of the left knee. B. hominis organisms were found in synovial fluid from the left knee. The patient responded dramatically to metronidazole treatment. B. hominis may become disseminated in immunosuppressed patients with diarrhoea and may cause infective arthritis. (AU)