PURPOSE: At present, further investigations are needed in patients with suspected pulmonary tuberculosis (TB) with negative sputum smear. The aim of this study was to evaluate the usefulness of whole blood IFN-γ assay and polymerase chain reaction (PCR) in the diagnosis of active pulmonary TB in stain negative patients who were suspected as active pulmonary TB.
METHODS: In this evaluation, we reviewed for all consecutive patients who were suspected as active pulmonary TB during the period from June 2006 to February 2008. One hundred sixty patients were suspected as having pulmonary TB during the period. After exclusion of stain positive TB (n=63), pleural TB (n=16), previous TB history (n=8) and denial to participate (n=8) cases, we conducted our study in 65 patients. QuantiFERON-TB Gold (Cellestis Ltd; Carnegie, Victoria, Australia) was used for IFN-γ assay.
RESULTS: Active TB was diagnosed in 27 of 65 participants (42%). The sensitivity, specificity and negative predictive value (NPV) of QFT-G for active TB were 81%, 81% and 86%, respectively. PCR was available in 59 patients. Nine of them showed positive results and all were diagnosed as active TB. The sensitivity, specificity and NPV of the test were 38%, 100% and 70%, respectively.
CONCLUSION: QFT-G and PCR can be used as a useful supplementary tool for the diagnosis of active TB in stain negative patients who are suspected as pulmonary TB if they had no history of previous TB in South Korea, where the prevalence of TB is intermediate.
CLINICAL IMPLICATIONS: Whole blood IFN-γ assay and PCR can be a useful supplementary tool for the early diagnosis of active TB in stain negative patients with no history of previous TB in South Korea, where the prevalence of TB is intermediate.
DISCLOSURE: Ju Han Song, No Financial Disclosure Information; No Product/Research Disclosure Information