Combination of MGIT liquid culture and Xpert MTB/RIF test in the rapid diagnosis and drug resistance detection in Mycobacterium tuberculosis / 中华检验医学杂志

ABSTRACT

Objective To evaluate the feasibility of Mycobacteria growth indicator tube ( MGIT ) liquid culture combined with rifampin resistance test real-time PCR ( Xpert MTB/RIF test) in the diagnosis of tuberculosis.Methods 652 cases of suspected pulmonary tuberculosis from October 2014 to March 2015 in Quzhou People′s Hospital were enrolled. The morning sputum samples were collected for acid-fast staining, L?wenstein-Jensen ( L-J) culture, BACTEC MGIT culture and Xpert MTB/RIF test.Samples with positive results of MGIT liquid culture were subjected to strain identification and drug sensitivity test with fluid method.Methodological comparison between four methods was made and the performance of MGIT liquid culture combined with Xpert MTB/RIF test in the rapid diagnosis and drug resistance detection in Mycobacterium tuberculosis was evaluated by chi-square test. Results Among the samples from 399 confirmed tuberculosis patients, the diagnostic sensitivity of the 4 methods ( acid-fast staining, L-J culture, MGIT culture and Xpert MTB/RIF test) were 17.0%(68/399), 23.8%(95/399), 37.8% (151/399) and 37.3%(149/399) respectively.The sensitivity and specificity of MGIT culture combined with Xpert MTB/RIF test was 39.8%(159/399) and 94.8%(240/253).The sensitivity of MGIT culture combined with Xpert MTB/RIF test was significantly higher than acid-fast staining (χ2 =50.9, P<0.01 ) and L-J culture (χ2 =23.7,P<0.01).The average detection time of MGIT culture was 7.5 days ( smear positive and Xpert MTB/RIF positive), 13.4 days (smear negative and Xpert MTB/RIF positive) and 16.9 days ( smear negative and Xpert MTB/RIF negative) .The sensitivity and specificity of Xpert MTB/RIF test in rifampin resistance detection were 9/9 and 97.3% ( 129/132 ) respectively.The average detection time of fluid method for drug sensitivity test was 8.3 days.Conclusions MGIT liquid culture combined with Xpert MTB/RIF test can detect Mycobacterium tuberculosis and the drug sensitivity rapidly.The method is highly sensitive and specific.It is important for clinical diagnosis and treatment of tuberculosis.