The Leukocyte Esterase Test Strip Is a Poor Rule-Out Test for Periprosthetic Joint Infection.

BACKGROUND: The urinary leukocyte esterase (LE) test strip has been suggested as a good screening test for periprosthetic joint infection (PJI). The purpose of this study is to compare the diagnostic profile of LE assays from different manufacturers and determine whether the LE test strip is a good rule-out test. METHODS: Synovial fluid samples (N = 344), sent to 1 laboratory for PJI testing, were used in this prospective study. Four different tests for synovial fluid LE were simultaneously evaluated for their performance in detecting white blood cell (WBC) positive samples (>3000 cells/µL). RESULTS: Both neutrophil elastase immunoassays demonstrated greater sensitivity than urinary LE test strips (92.0% and 90.8% vs 72.4% and 80.3%; all P < 0.011). Fifty-three percent of false-negative urinary LE test strip results clearly missed the presence of elevated levels of synovial fluid LE. Invalid urinary LE test strip results were 4-fold more likely among WBC (+) compared with WBC (-) samples (27.0% vs 6.8%; P < 0.0001). The combined failure to detect an elevated WBC count, because of either false-negative or invalid results, was 47.1% and 41.4% for the Roche and Siemens test strips, respectively. CONCLUSIONS: This study agrees with the existing literature demonstrating that the LE test strips are among the lowest sensitivity tests for PJI. The urinary LE tests strips should not be used to rule-out PJI, as they often fail to detect abundant levels of LE in synovial fluid. Instead, it is more appropriate to use the (++) LE test strip result as a secondary confirmatory rule-in test for PJI because of its high specificity.

Pathological manifestations in murine Lyme disease: association with tissue invasion and spirochete persistence.

The clinical manifestations of human Lyme disease present with a spectrum of tissue or organ involvement and severity of symptoms. The murine model of Lyme disease has proved to be an accurate reflection of many of the human symptoms of disease and has been particularly useful for studying development of subacute arthritis and tendonitis. Direct tissue invasion by Borrelia burgdorferi and persistence of high levels of spirochetes in tissues are important components of arthritis development. The outer-surface lipoproteins contain a biologically active lipid-modified moiety with potent ability to stimulate inflammatory cytokine production and other inflammatory mediators such as nitric oxide. Localized inflammation stimulated by these lipoproteins may be the trigger for neutrophil infiltration, synovial proliferation, and other events associated with this arthritis. Invasion of maternal uterine tissue, but not direct invasion of fetal tissue, is associated with low levels of pregnancy loss in mice infected during gestation, consistent with the detrimental effect of inflammatory cytokines on pregnancy.

[Value of the assay of protein SAA and urinary antitrypsin activity in osteoarticular infections]. / Intérêt du dosage de la protéine SAA et de l'activité antitrypsique urinaire dans les infections ostéo-articulaires.

Erythrocyte sedimentation rate is normal in 20% to 25% of patients with discitis due to common pathogens. We evaluated serum amyloid A (SAA) protein and urinary trypsin inhibitory activity in osteoarticular infections comparatively with erythrocyte sedimentation rate and serum C-reactive protein in 20 patients including 14 with discitis due to common pathogens and 6 with septic arthritis. Assays were performed on D0, D8, D15, D30, and D60 after initiation of antimicrobial therapy. On D0, all four markers were significantly higher in patients with septic arthritis than in patients with discitis. C-reactive protein levels exhibited the fastest kinetics with a return to normal values within 15 days in both conditions. Urinary trypsin inhibitory activity was only slightly elevated in patients with discitis and returned to normal within 30 days in both conditions. Serum amyloid A levels required 30 to 60 days to return to normal. Erythrocyte sedimentation rate exhibited the slowest kinetics, with normal values being achieved only after 60 days. Although simple, rapid, and inexpensive, urinary trypsin inhibitory activity determination exhibits poor sensitivity. Serum amyloid A assay is not routinely available but may be a valuable parameter for monitoring patients whose erythrocyte sedimentation rate and C-reactive protein level are normal (as in 2 of our patients with discitis).

Renal affection in patients with ankylosing spondylitis and psoriatic arthritis.

In a retrospective study of 148 patients with well-defined ankylosing spondylitis (AS), psoriatic arthritis (PSA) or reactive arthritis (ReA) an 11% prevalence of idiopathic hematuria, proteinuria, or cylinduria was found in the former two groups. None of the patients with ReA had unexplained pathological urinary findings. Such findings were associated with raised ESR and presence of peripheral arthritis in AS and with the duration of disease in PSA. No patient lacking sacroiliitis showed pathological urinary findings. We believe that such findings may reflect nephropathy associated with AS and PSA.

[Calcium, phosphorus, hydroxyproline and nitrogen in inflammatory joint diseases]. / Zum Studium des Calciums, Phosphors, Oxyprolins und Stickstoffs bei entzündlichen Gelenkerkra nkungen

The elimination of calcium, phosphorus, hydroxyproline and nitrogen was studied in 127 patients with inflammatory joint diseases and )6 healthy controls for 4 days. On the third day, 186 mg of calcium was administered intravenously. Provoked hypercalciuria tests were made in 35 males, 116 females with rheumatiod arthritis (RA), 18 males with ankylosing spondylitis (ASp), 8 postinfectious arthritis (PA) and 18 healthy controls (C). In 120 patients comparison was made between the ratios of eliminated P/hydroxyproline, Ca/hydroxyproline and P/Ca with regards to the results obtained in healthy controls. The kinetics of 47Ca were studied in 7 males with ASp and 4 C. The ratios Ca/P in serum and P/Ca in urine were studied in the same patients and compared with 21 C. The results show that the bone symptomatology of PA manifests itself by elimination of elevated amounts of all of the indicators studied, especially phosphorus. In RA there may be considerable oscillations of flow of urine due to the perspiration of patients. RA differs from decompensated coxarthrosis and gonarthrosis in that the patients eliminate significantly less calcium and phosphorus. Corticosteroids stimulate the elimination of hydroxyproline. Younger patients with RA (25-44) show changes compatible with osteoporosis, older females (45-64) display changes similar to those seen in osteomalacia, the oldest female patient (65-84) appear to have insufficient binding capacity for calcium. The hyposthesis is proposed that at the disease onset RA is characterized by an extremely marked syndrome of osteopathy. ASp is characterized by significantly reduced elimination of hydraxyproline, higher metabolic pool of calcium, lower elimination of calcium in urine and faeces and lower accretion to bone.