Abstract:

Objective To investigate the application value of GeneXpert MTB/RIF (GeneXpert) in the diagnosis of knee tuberculosis and the detection of rifampicin resistance. Methods Clinical data of 66 patients with suspected knee tuberculosis admitted to Hebei Chest Hospital from July 2015 to March 2019 were collected. According to the diagnostic criteria, 44 cases were diagnosed with knee tuberculosis and the other 22 cases were diagnosed with non-tuberculous knee infection. Pustus samples were taken intraoperatively for acid-fast staining, GeneXpert detection, and rapid culture by BACTEC MGIT 960 liquid culture system of Mycobacterium tuberculosis (liquid culture), among which, drug resistance was detected by modified Roche absolute concentration drug sensitivity test in samples with positive results. The detection efficiency of acid-fast staining, GeneXpert detection and liquid culture was evaluated based on clinical diagnosis. Results Of the 66 samples, 25 were positive and 41 were negative in liquid culture. Of the 25 positive specimens, 4 were resistant to rifampicin and 21 were sensitive to rifampicin. Fourteen smears were positive in acid fast staining and 51 smears were negative. As to results of GeneXpert, 35 were positive and 31 were negative, and 4 were resistant to rifampicin. According to clinical diagnosis, the sensitivities of GeneXpert detection, acid-fast staining and liquid culture were 75.0% (33/44), 29.5% (13/44) and 52.3% (23/44), respectively; the specificities were 90.9% (20/22), 95.5% (21/22) and 90.9% (20/22), respectively. rpoB gene mutation was also detected by GeneXpert in the 4 samples that showed resistance to rifampicin in drug sensitivity test. Conclusion GeneXpert detection could simultaneously detect Mycobacterium tuberculosis and the drug resistance to rifampicin in knee effusion, the sensitivity was high and it had good application value.

Key words: Tuberculosis, Knee joint, Polymerase chain reaction, Rifampin, Evaluation studies