title: Diagnostic usefulness of a T-cell-based assay for osteoarticular tuberculosis.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  A negative ELISPOT assay using PBMC may be a useful test for excluding a diagnosis of active osteoarticular TB.
authors.affiliation: 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.
authors.forename: Oh-Hyun
authors.initials: OH
authors.lastname: Cho
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Park
authors.forename: Ki-Ho
authors.initials: KH
authors.lastname: Park
authors.forename: Yong Pil
authors.initials: YP
authors.lastname: Chong
authors.forename: Heungsup
authors.initials: H
authors.lastname: Sung
authors.forename: Mi-Na
authors.initials: MN
authors.lastname: Kim
authors.forename: Sang-Oh
authors.initials: SO
authors.lastname: Lee
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Jun Hee
authors.initials: JH
authors.lastname: Woo
authors.forename: Yang Soo
authors.initials: YS
authors.lastname: Kim
authors.forename: Sung-Han
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D058501:Enzyme-Linked Immunospot Assay / Q000379:methods*; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011933:Reagent Kits, Diagnostic; D013601:T-Lymphocytes / Q000378:metabolism*; D014394:Tuberculosis, Osteoarticular / Q000097:blood / Q000175:diagnosis*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma