The polymerase chain reaction of the sputum for the diagnosis of pulmonary tuberculosis in HIV-infected patients

Abstract

There are many laboratory methods for confirmation of the diagnosis of pulmonary tuberculosis with various sensitivity, specificity, advantage or disadvantage. The objective of this research is to study the validity of the polymerase chain reaction (PCR) method of the sputum for the diagnosis of pulmonary tuberculosis in cases of HIV-infected patients, compared with the sputum mycobacterial culture as the gold standard. Patients who were diagnosed as having pulmonary tuberculosis and HIV infection with the mean CD4 less than 200/mm³ during 1 Sep 2013 – 1 Sep 2015 in the department of Medicine, Maharat Nakhon Ratchasima Hospital, were retrospectively studied. Only 93 patients who had concurrently sputum tested for PCR method and biological culture were recruited and 84 of them had positive culture for M. tuberculosis whereas 9 had negative culture. The calculated sensitivity and specificity were 90.3 % and 100 %, respectively. The positive predictive value and negative predictive value were 100 % and 0 %, respectively. Likewise the sensitivity and specificity of sputum AFB stain were 86.0 % and 100 %, respectively. In conclusion, The PCR of the sputum for TB had very high sensitivity and specificity and should be used after negative AFB stain. Furthermore, it was able to detect the mycobacterial resistance to Isoniazid as well as Rifampicin leading to the early and proper management for tuberculosis.