RESUMO
<p><b>BACKGROUND</b>Interferon-gamma release assay (IGRA) has been used in latent tuberculosis (TB) infection and TB diagnosis, but the results from different high TB-endemic countries are different. The aim of this study was to investigate the value of IGRA in the diagnosis of active pulmonary TB (PTB) in China.</p><p><b>METHODS</b>We conducted a large-scale retrospective multicenter investigation to further evaluate the role of IGRA in the diagnosis of active PTB in high TB-epidemic populations and the factors affecting the performance of the assay. All patients who underwent valid T-SPOT.TB assays from December 2012 to November 2015 in six large-scale specialized TB hospitals in China and met the study criteria were retrospectively evaluated. Patients were divided into three groups: Group 1, sputum culture-positive PTB patients, confirmed by positive Mycobacterium tuberculosis sputum culture; Group 2, sputum culture-negative PTB patients; and Group 3, non-TB respiratory diseases. The medical records of all patients were collected. Chi-square tests and Fisher's exact test were used to compare categorical data. Multivariable logistic analyses were performed to evaluate the relationship between the results of T-SPOT in TB patients and other factors.</p><p><b>RESULTS</b>A total of 3082 patients for whom complete information was available were included in the investigation, including 905 sputum culture-positive PTB cases, 914 sputum culture-negative PTB cases, and 1263 non-TB respiratory disease cases. The positive rate of T-SPOT.TB was 93.3% in the culture-positive PTB group and 86.1% in the culture-negative PTB group. In the non-PTB group, the positive rate of T-SPOT.TB was 43.6%. The positive rate of T-SPOT.TB in the culture-positive PTB group was significantly higher than that in the culture-negative PTB group (χ2 = 25.118, P < 0.01), which in turn was significantly higher than that in the non-TB group (χ2 = 566.116, P < 0.01). The overall results were as follows: sensitivity, 89.7%; specificity, 56.37%; positive predictive value, 74.75%; negative predictive value, 79.11%; and accuracy, 76.02%.</p><p><b>CONCLUSIONS</b>High false-positive rates of T-SPOT.TB assays in the non-TB group limit the usefulness as a single test to diagnose active TB in China. We highly recommend that IGRAs not be used for the diagnosis of active TB in high-burden TB settings.</p>
RESUMO
Objective To investigate the distribution of polymorphisms of SLC11A1 gene,VDR gene,MBL gene and IFNG gene with susceptibility to tuberculosis (TB) in Chinese Han population suffering from drug-sensitive TB and drug-resistant TB so as to identify the correlation between gene polymorphisms and the development of drug-resistant TB.Methods Single nucleotide polymorphisms (SNP) of VDR gene,SLC11A1 gene,MBL gene,IFNG gene were typed and analyzed by pyrosequencing,Real-time Probe and SNaPshot among 229 patients with drug-sensitive TB and 230 patients with drug-resistant TB.Results The polymorphic foci of VDR gene from the drug-sensitive TB group and the drug-resistant TB group showed no significant difference (P＞0.05).The genotype of INT4 site and allelic frequency of SLC11A1 gene for drug-sensitive TB group were significantly different from those for drug-resistant TB group(P=0.031,0.046).If recessive inheritance was assumed,the genotypes of INT4 site from the two groups were significantly different (0R=5.756,95% CI:1.261-26.269,P=0.011).Considering the relationship between OR values under various combination,our findings confirmed that the genetic mode of INT4 site was in accordance with recessive inheritance.The genotypes of Q/P site and allelic frequencies of MBL gene from drug-sensitive and drug-resistant groups were significantly different (P=0.029,0.033).The difference still existed under the hypothesis of recessive inheritance (OR=9.290,95% CI:1.167-73.949,P=0.011).The polymorphic foci of IFNG gene from the two groups showed no significant difference.Conclusion INT4 sites on SLC11A1 gene and Q/P site on MBL gene were probably associated with the development of drug-resistant TB in Chinese Han population.Further study on this issue would be helpful in locating the population at high risk of drug-resistant TB and exploring the effective intervention to decrease the incidence of this disease.