Abstract:

Objective BACTEC MGIT 960 (MGIT 960) and fluorescence PCR melting curve method (PCR melting curve method) were used to detect the etiology and drug resistance of different surgical specimens of tuberculous empyema, and comparative study was conducted. Methods From January 2019 to June 2020, 150 patients with tuberculous empyema were enrolled (MTB MGIT 960 was positive and MPB64 monoclonal antibody was MTB strain of thoracic puncture before surgery, or histopathological examination showed typical tuberculous granulomatous inflammation with caseous necrosis). MGIT 960 liquid culture, phenotypic drug sensitivity test (drug sensitivity test) and PCR melting curve method were used to detect nucleic acid and drug resistance genes of different surgical specimens (150 lesions and 150 pus). Positive rate of etiological diagnosis between two kinds of techniques in different surgical specimens, and drug resistance results of 40 pathogenic positive cases (copies) detected by two kinds of techniques at the same time were comparatively analyzed. Results In 300 surgical specimens (pus and tissue), the overall positive rate of MTB detection by PCR fusion curve method (44.0%, 132/300) was significantly higher than that of MGIT 960 (18.0%, 54/300) (χ²=47.405, P=0.000). The positive rate of PCR melting curve nucleic acid detection in tissue samples (50.0% (75/150)) was significantly higher than that in pus samples (38.0%, (57/150)) (χ ²=4.383, P=0.048); while the positive rate of MGIT 960 in tissue samples (12.7% (19/150)) was significantly lower than that in pus samples (23.3% (35/150)) (χ ²=5.781, P=0.024). Further analysis of the positive rate of MGIT 960, fluorescent PCR and two combined techniques in etiological diagnosis of 150 patients was made (if one of the methods is positive, the patient woulde be judged pathogenic positive). The results showed that the positive rate of the former (30.7% (46/150)) was significantly lower than those of the latter two (66.7% (100/150) and 70.7% (106/150), respectively) (χ ²=38.908, 48.009; both P=0.000), no significant difference was found between the latter two (χ ²=0.558, P=0.455). The results of drug resistance of 40 pathogenic positive cases (copies) detected by two methods at the same time showed that the detection rates of isoniazid, rifampicin, ethambutol, streptomycin and levofloxacin by MGIT 960 and PCR melting curve method were 20.0% (8/40) and 17.5% (7/40), 17.5% (7/40) and 15.0% (6/40), 17.5% (7/40) and 17.5% (7/40), 17.5% (7/40) and 22.5% (9/40), 5.0% (2/40) and 7.5% (3/40), respectively, and the differences were not significant (χ ²=0.082, 0.092, 0.000, 0.313, 0.213, all P>0.05). Conclusion In tuberculous empyema patients, the overall positive rate of MTB detected by PCR melting curve method was significantly higher than that of MGIT 960 culture, and the positive rate of tissue samples was higher than that of pus samples; the detection rate of drug resistance was similar to that of MGIT 960 phenotype drug sensitivity test, which could quickly detect the etiology and drug resistance.

Key words: Empyema,tuberculous, Specimen Handling, Polymerase chain reaction, Molecular diagnostic techniques, Tuberculosis,multi-drug resistant, Microbial sensitivity tests, Comparative study