Evaluation of a PCR-amplified IS6110 insertion element in the rapid diagnosis of pulmonary tuberculosis in comparison to microscopic methods in Sudan.

OBJECTIVE The aim of this study was to evaluate the sensitivity and specificity of a polymerase chain reaction (PCR)-based method (IS6110 insertion site) in the diagnosis of pulmonary tuberculosis in sputum samples in comparison to smears by using culture on Loewenstein-Jensen medium as a standard. METHODS The study was conducted during the period 1999 through to 2000, at Khartoum Teaching Hospital, Sudan, on 200 sputum samples. The samples were collected from patients suspected of having pulmonary tuberculosis, were examined using a PCR amplified IS6110 insertion element in comparison to Ziehl-Neelsen stained smears in terms of sensitivity and specificity. Culture on Loewenstein-Jensen medium was used as the standard to control the 2 tests. RESULTS Microscope sensitivity was found to be 65.4% and the specificity was 90.5%, whereas sensitivity of the IS6110 was 88.5% and specificity was 98.6%. CONCLUSION The study concluded that though IS6110 sensitivity was 13.1% higher than smear method, it provided a significant improvement in specificity for the diagnosis of pulmonary tuberculosis. Improvement is still needed to increase the sensitivity of the IS6110 methods by decreasing the number of the false negative samples before its use can be at routine levels.