575. Indeterminate Test Results of T-SPOT.TB in Patients with Suspected Extrapulmonary Tuberculosis Performed in Routine Clinical Practice
Session: Poster Abstract Session: Mycobacterial Diagnostics
Friday, October 21, 2011
Room: Poster Hall B1

Background: Two interferon- g releasing assays – QuantiFERON-TB Gold and T-SPOT.TB- which are the useful tools for rapid diagnosis of tuberculosis (TB), can have indeterminate test results (ITR). While there are some studies that demonstrated risk factors for ITR in QuantiFERON-TB Gold, a few studies have evaluated those in T-SPOT.TB. The aim of this study was to investigate risk factors associated with ITR in T-SPOT.TB.

Methods: From April 2008 to August 2010, all patients with suspected extrapulmonary tuberculosis (E-TB) were enrolled at a tertiary hospital in an intermediate TB-burden country. ITR was defined as the number of spots in the positive control well was < 20 or the number of spots in the negative control well was > 10.

Results: Of a total of 368 patients, 32 (8.7%, 95% CI 6.0-11.7) had the ITR on the T-SPOT.TB test. ITR were due to low mitogen response in 13 (40.6%) patients and high nil response in 19 (59.4%) patients. Univariate and multivariate analysis revealed that old age, underlying disease, immunosuppressive conditions, lymphopenia, and clinical manifestation of E-TB were not significantly associated with ITR. The detailed data are shown in Table.

Conclusion: Indeterminate results in T-SPOT.TB under routine clinical practice were not infrequent. Our study showed that ITR in T-SPOT.TB may be not affected by age, underlying disease, immunosuppressive conditions, lymphopenia, and clinical manifestation of E-TB, compared to the data on ITR with QuantiFERON-TB Gold.

Subject Category: D. Diagnostic microbiology

Yumi Lee, MD, Sun-Mi Kim, PhD, Su-Jin Park, Gwang Beom Go, M.D., Ki-Ho Park, MD, Sang-Oh Lee, MD, Sang-Ho Choi, MD, PhD, Yang Soo Kim, MD, PhD, Jun Hee Woo, MD, PhD and Sung-Han Kim, MD, PhD, Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea


Y. Lee, None

S. M. Kim, None

S. J. Park, None

G. B. Go, None

K. H. Park, None

S. O. Lee, None

S. H. Choi, None

Y. S. Kim, None

J. H. Woo, None

S. H. Kim, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.