Value of molecular biology method in detection of Mycobacterium tuberculosis and its drug resistance

ObjectiveTo explore the value of molecular biology method in the detection of Mycobacterium tuberculosis (MTB) and its drug resistance.

MethodsThe accuracy, minimum detection limit and detection period of Xpert MTB/RIF assay, gene chip assay, modified Roche culture assay and proportion assay in detecting MTB were analyzed using standard MTB strain H37Rr as control, and single-drug resistant and multi-drug resistant MTB diluted gradiently as the test sample.

ResultsThe minimum detection limit of modified Roche culture assay and Xpert MTB/RIF assay was 3×10² cfu/mL, which was 3×10⁴ cfu/mL for gene chip assay.Xpert MTB/RIF assay resulted in false-positive rifampicin resistance when the concentration was 3×10² cfu/mL, and could not detect isoniazid resistance.The detection period of Xpert MTB/RIF assay was ≤ 2 h, which was ≤ 8 h for gene chip assay, and five to eight weeks for modified Roche culture assay and proportion assay.

ConclusionsIn the detection of MTB and its drug resistance, molecular biology methods have obvious advantages in detection period, and each method has its own advantages in the minimum detection limit and accuracy.The economic level and critical degree of patients should be considered in the clinical diagnosis, so to choose appropriate detecting method.