The Value Of Combined Detection Of Multiple Indices For Diagnosis Of Culture Negative Tuberculosis

Tuberculosis, a major infectious disease which endangers overall humanity, is a crucial issue of public health and serious social problem. China, following India, confirmed the second largest TB---infected population in the world. Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, with respiratory droplets as the principle media of transmission. Bacteriological examination of TB is a major means of identifying the sources of TB infection, as well as the important basis for TB confirmation and chemotherapy regimens. Culture negative tuberculosis, accounting for about 40%-60% of all the TB diagnosis, is classified as an active TB with negative type based on the respective detections of sputum mycobacterium and sputum smear acid fast bacilli. Due to the hidden symptoms of culture negative tuberculosis, some patients may convert to smear---positive pulmonary tuberculosis, if they fail to get timely diagnosis and treatment. The key to the effective diagnosis and treatment of tuberculosis is early discovery, early diagnosis, and early treatment with early diagnosis on the top. Nowadays, there are multiple methods of TB diagnosis: the chest imaging detection, bacteriology inspection, immunological diagnosis, cytokines detection, molecular diagnosis, and etc. as the common clinical practices. But each of these methods has certain limitations, resulting in the failure of timely and prompt diagnosis of culture negative tuberculosis. Culture negative tuberculosis is always subjected to misdiagnosis or missed diagnosis due to the lack of conclusive evidence of bacteriological examination, merely based on such general analysis as medcal history, symptoms, chest X-ray, chest CT, laboratory examination, and etc. Therefore, the diagnosis of culture negative tuberculosis undergoes considerable difficulties. With the development of laboratory examination technology, the discovery and application of various diagnostic methods can improve the early diagnosis of culture negative tuberculosisObjective:To investigate the value of determination of DNA from Mycobacterium tuberculosis(TB-DNA) obtained from the sputum or bronchoalveolar lavage fluid subjected to fluorescent quantitative PCR, Myco Dot Three, test results of purified protein derivative(TB-PPD) and test results of interferon gamma release assay(IGRA) from blood(T-SPOT) in the diagnosis of culture negative tuberculosis.Methods:Collecting 227 cases of the outpatients and inpatients from the Tuberculosis Department and the Respiration Department, Hebei Provincial Chest Hospital during the period from November, 2013 to November, 2014, including 135 male cases and 92 female cases, aged 15 to 77 years with the average age of 47.5 years old.The group of initial treatment of culture negative tuberculosis: 118 cases in total, including 62 male cases and 56 female cases, aged 16-73 years old with the average age of 45.1 years old. The selected patients all had the typical clinical manifestations and their chest X-ray or chest CT has the features of active tuberculosis, ruling out other non---tuberculous pulmonary diseases, and these cases are consistent with the diagnostic criteria of active pulmonary tuberculosis in “Guidelines of Tuberculosis Diagnosis and Treatment” stipulated by the Tuberculosis Branch of Chinese Medical Association in 2001. This group is mainly for assessing the diagnostic value of combined detection indices.The group of initial treatment of culture positive tuberculosis: 49 cases in total, including 31 male cases and 18 female cases, aged 15-76 years old with an average age of 42.9 years old. All the selected patients met the international diagnotic standard of infectious pulmonary tuberculosis. This group is mainly for evaluating the sensitivity of the detection indices.The group of Non---tuberculous diseases: 60 cases in total, including 39 male cases and 21 female cases, aged 15-77 years old with an average age of 47.1 years old. These include 15 cases of chronic obstructive pulmonary disease, 13 cases of lung cancer, 11 cases of pneumonia, 8 cases of bronchiectasis, and 13 other cases(5 cases of lung cyst, 3 cases of spontaneous pneumothorax, and 5 cases of bronchial asthma). These patients, with relevant inspections, were properly diagnosed, excluding the possibility of combined tuberculosis. This group is mainly for evaluating the specificity of the detection methods.The Statistical Method:The data were analyzed by applying the statistical software SPSS 17.0, the significant test comparison between count data groups was with χ2 test, P<0.05 with the consideration that the difference had statistical significance.Results:1 The specificity of all the indices through TB-DNA detection, Myco Dot Three, PPD test and T-SPOT reach more than 90%. The positive rate of the group with culture negative tuberculosis fluctuates between 23.73%-42.37%, and the positive rate of the group with culture positive tuberculosis fluctuates between 67.39%-93.88%, both higher than the group with non---tuberculous diseases. In particular, among all the indices, those of T-SPOT are obviously higher than those of the other 3 methods. The differences are statistically significant(P<0.05).2 With the increase of combined indices, the positive detection rate of culture negative tuberculosis also gradually increases. The involvement of T-SPOT detection of the above–mentioned 2 and 3 methods is higher than that without T-SPOT detection, the difference being statistically significant(P<0.05). The detection rate of combined detection is notably increased compared with the single method.3 Through all the 4 combined indices of TB-DNA detection, Myco Dot Three, PPD test and T-SPOT, the specificity of 2, 3 and 4 combined methods is close to 100%. The simultaneous positive detection rates of the group ungergoing their initial treatment with culture positive tuberculosis with 2, 3, 4 combined methods reach 67.35%, 59.18%, 28.57% respectively. The differences compared with the group of non---tuberculous diseases have statistical significance(P<0.05).4 Through all the 4 combined indices of TB-DNA detection, Myco Dot Three, PPD test and T-SPOT, the simultaneous positive detection rates of the group undergoing their initial treatment of culture negative tuberculosis with 2, 3 and 4 combined methods reach 44.92%, 17.8%, 4.24% respectively. The differences between the group whose simultaneous positive detection rates were with 2 and 3 combined methods and the group of non---tuberculous diseases have statistical significance(P<0.05), however the differences between the group with 4 combined methods and the group of non---tuberculous diseases have no statistical significance(P>0.05).Conclusions:Compared with single detection methods, the combined detection of TB-DNA detection, Myco Dot Three, PPD test and T-SPOT with multiple indices can improve the sensitivity in diagnosing culture negative tuberculosis. In particular, with the combined detection participated by T-SPOT, the detection rate of culture negative tuberculosis is considerably increased.