RESUMO
BACKGROUND: Mycobacterium tuberculosis (MTB) infection is a global health problem. Failure to accurately identify cases of active MTB has serious effects on both patients and the community. Acid-fast bacilli (AFB) smear has poor sensitivity and culture methods have a delay ranging from 1 to 8 weeks for diagnosis. Nucleic acid amplification assays may be suitable candidates for this purpose. PATIENTS AND METHODS: In a prospective study, we evaluated Mycobacterium tuberculosis DNA in peripheral blood samples with PCR technique in 190 patients with pulmonary and extra pulmonary tuberculosis whom were admitted to Tehran Imam Khomeini hospitals during 2006-2010. Three ml citrated blood samples were obtained from cases. DNA extraction was performed by QIAGEN commercial kit and PCR performed with IS1081 Primer. RESULTS: Fifty six cases had extra-pulmonary tuberculosis and 134 were pulmonary. Overall sensitivity and specificity of the PCR assay was 41.1% and 95.5%, respectively. CONCLUSIONS: MTB-PCR assay on PBMC using IS1081 primer has a low sensitivity and now can not use as a single or alternative diagnostic test for tuberculosis. However, with regard to its high specificity can use for help diagnosing of TB in cases have no enough sputum (or other specimens) to examination for acid-fast bacilli (AFB) smear and culture.