Evaluation of the Xpert MTB/RIF assay for diagnosis of tuberculosis and rifampin resistance in county-level laboratories in Hunan province, China.
BACKGROUND
The Xpert MTB/RIF showed high sensitivity and specificity in previous studies carried out in different epidemiological and geographical settings and patient populations in high-burden tuberculosis (TB) countries. However, there were little data obtained by validation or demonstration study of the assay in China. In this study, the performance of Xpert MTB/RIF was investigated in two county-level laboratories in Hunan Province, China.


METHODS
Consecutive patients with suspected pulmonary tuberculosis (PTB) and suspicion for multidrug-resistant tuberculosis (MDR-TB) were enrolled. For each patient suspected to have PTB, three sputum specimens (one spot sputum, one night sputum, and one morning sputum) were collected and each sputum was tested with smear microscopy, Löwenstein-Jensen (LJ) culture, and Xpert MTB/RIF test. For comparison across subgroups and testing methods, 95% confidence intervals were calculated. All analyses were done with SPSS 16.0, and P < 0.05 was regarded as significant.


RESULTS
For case detection, the sensitivity of Xpert MTB/RIF was 100% for smear- and culture-positive TB and 88.6% for smear-negative and culture-positive TB; the overall sensitivity was 94.5% for all culture-positive patients. The specificity was 99.8%. The sensitivity of Xpert MTB/RIF assay was 22.0% in clinical TB patients and the specificity reached 100.0% in the group of patients who are infected with nontuberculous mycobacteria. For the detection of rifampin resistance, the sensitivity of MTB/RIF RIF-resistance detection was 92.9%, and the specificity was 98.7%. Of the 26 Xpert MTB/RIF-positive and RIF-resistant patients confirmed by LJ proportion tests, 20 (76.9%) patients were infected by MDR-TB.


CONCLUSIONS
The Xpert MTB/RIF assay is a highly sensitive and specific method for diagnosis of TB and RIF resistance, which will enable it to have the potential to be used in county-level laboratories and lead to the reduction of the infectious pool and improvements in TB control in China. Further evaluations in county-level laboratories for implementing the assay are still required.
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Peilei
P
Hu
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Liqiong
L
Bai
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Fengping
F
Liu
National Tuberculosis Reference Laboratory, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
Xichao
X
Ou
Tuberculosis Program Office, Program for Appropriate Technology in Health, Beijing 100022, China.
Zhiying
Z
Zhang
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Songlin
S
Yi
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Zhongnan
Z
Chen
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Daofang
D
Gong
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Binbin
B
Liu
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China.
Jingwei
J
Guo
Hunan Provincial Tuberculosis Reference Laboratory, Hunan Provincial Institute for Tuberculosis Control and Prevention, Changsha, Hunan 410013, China. Email: tanyunhong@163.com.
Yunhong
Y
Tan
D000328:Adult; D000904:Antibiotics, Antitubercular / Q000627:therapeutic use; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012293:Rifampin / Q000627:therapeutic use*; D014376:Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy*; D018088:Tuberculosis, Multidrug-Resistant; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000188:drug therapy; D055815:Young Adult
D000904:Antibiotics, Antitubercular; D012293:Rifampin