Clinical evaluation of an in-house IS6110 polymerase chain reaction for diagnosis of tuberculosis

The aim of this study was to clinically validate a heminested polymerase ch ain reaction (PCR) method, based on the IS6110 insertion segment of Mycobac terium tuberculosis complex, for the diagnosis of tuberculosis. Samples of pulmonary, extrapulmonary and blood origin were collected prospectively fro m 331 patients, All samples were processed to detect acid-fast bacilli by d irect stain, culture and PCR, The gold standard comparison was a clinically based final case definition of tuberculosis corresponding to group 3 of th e American Thoracic Society's classification system. The sensitivities of s tain, culture and PCR were 41%, 65% and 59%, respectively. Overall specific ity exceeded 97% for all techniques. The combination of PCR and direct stai n achieved a sensitivity similar to that of culture alone. The PCR method d etected 74 of 95 (78%) culture-positive results. In a hospital setting, PCR could be a useful, reliable tool for diagnosis of tuberculosis and may be introduced as a complementary routine diagnostic laboratory method.