Cho OH, Park SJ, Park KH, et al. Diagnostic usefulness of a T-cell-based assay for osteoarticular tuberculosis

Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Pungnap-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
The Journal of infection (Impact Factor: 4.44). 09/2010; 61(3):228-34. DOI: 10.1016/j.jinf.2010.06.015
Source: PubMed


Although diagnosing osteoarticular tuberculosis (TB) remains a challenge, a recently developed Mycobacterium tuberculosis-specific ELISPOT assay for diagnosing TB infection has shown promising results. We performed a prospective, blinded, observational study to compare its diagnostic usefulness with those of conventional tests in patients with suspected osteoarticular TB.
All patients presenting at a tertiary hospital between April 2008 and September 2009 with suspected osteoarticular TB were enrolled. In addition to conventional tests for TB, we used ELISPOT assays to measure the IFN-gamma response to ESAT-6 and CFP-10 in T-cells in samples of peripheral blood mononuclear cells (PBMC). Patients with suspected osteoarticular TB were classified by diagnostic category.
Of the 65 patients with suspected osteoarticular TB, 5 (8%) were excluded due to inconclusive diagnoses. Of the remaining 60 patients, 23 (38%) were classified as having confirmed TB, 3 (5%) as having probable TB, 2 (3%) as having possible TB, and 32 (53%) as not having active TB. Five (8%) patients with probable or possible TB were excluded from the final analysis. Of the 23 patients with confirmed osteoarticular TB, 15 (65%) had TB spondylitis, 4 (17%) had TB arthritis, 2 (9%) had prosthetic joint infection, and 2 (9%) had extra-spinal TB. The sensitivities of the tuberculin skin test (> or =10 mm) and the ELISPOT assay for active osteoarticular TB were 80% (95% confidence interval [CI], 58%-92%) and 100% (95% CI, 85%-100%) (P = 0.04), respectively and their specificities were 68% (95% CI, 51%-81%) and 58% (95% CI, 41%-74%) (P = 0.60), respectively.
A negative ELISPOT assay using PBMC may be a useful test for excluding a diagnosis of active osteoarticular TB.

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Available from: Ki-Ho Park, Jan 01, 2016
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    • "All patients were independently classified by two independent study investigators (O-H Cho and S-H Kim), without knowledge of the T-SPOT.TB test results, on the basis of clinical, histopathological, radiological, and microbiological information collected over at least 3 months of follow-up. The clinical categories of patients with suspected E-TB have been previously described [3,6,7,11,14]. Briefly, patients classified as having confirmed TB were those with clinical specimens positive for M. tuberculosis by culture or by PCR. "
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    ABSTRACT: The two interferon-γ release assays such as QuantiFERON-TB Gold / In-Tube (QFT-TB) and T-SPOT.TB-are useful tools for the rapid diagnosis of tuberculosis (TB) but can yield indeterminate test results (ITRs). While some studies have identified risk factors for ITRs in the QFT-TB test, there have been few such studies for the T-SPOT.TB test. The aim of this study was to investigate the risk factors associated with ITRs in the T-SPOT.TB test. From April 2008 to August 2010, all patients with suspected extrapulmonary tuberculosis (E-TB) were enrolled in a tertiary hospital in Korea. ITR was defined as < 20 spots in the positive control well or > 10 spots in the negative control well. Out of a total of 368 patients, 32 (8.7%, 95% CI, 6.0% to 11.7%) had ITRs in their T-SPOT.TB tests. The ITRs were due to a low mitogen response in 13 (40.6%) patients and to a high nil response in the other 19 (59.4%) patients. Statistical analysis revealed that old age, underlying diseases, immunosuppressive treatment, lymphopenia, and clinical manifestations of E-TB were not significantly associated with ITRs. Indeterminate results in the T-SPOT.TB test are not affected by age, underlying disease, immunosuppressive treatment, lymphopenia, or clinical manifestations of E-TB, which are known risk factors for indeterminate results in the QFT-TB test.
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    ABSTRACT: Background: Limited data are available for the clinical utility of serial interferongamma producing T-cell response after initiation of treatment in patients with extrapulmonary tuberculosis (TB). We studied the serial TB-specific antigen T-cell responses measured using the T-SPOT.TB assay during the course of therapy. Material and Methods: We prospectively enrolled adult patients who were newly diagnosed with active extrapulmonary TB over a 24-month period. All patients were given standard anti-TB treatment. Blood samples were obtained for T-SPOT. TB at diagnosis, as well as 1-, 3-, 6-, and 12-months after initiating anti-TB therapy. Results: A total of 52 patients with extrapulmonary TB (38 confirmed and 14 probable TB) were included in the final analysis. All patients had clinical and radiologic improvement after treatment and cured. T-SPOT.TB was positive for 90% at diagnosis, 100% at 1-, 3-, and 6-months, and 93% at 12-months after initiation of anti-TB therapy. There was no significant difference in median T-cell response between early secreting antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) at all time points. Median T-cell response steadily increased up to 6 months and then decreased. Conclusions: T-SPOT.TB assay remained positive after successful anti-TB treatment in most patients with extrapulmonary TB. Our data suggests that serial T-SPOT.TB has limited clinical utility as a surrogate marker of treatment response in patients with extrapulmonary TB.
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