Abstract:

Objective To evaluate the application of PNB/TCH growth test, Mycobacterium tuberculosis antigen (MPB64) detection and PCR-fluorescent probe method in identification of Mycobacterium tuberculosis complex (MTBC) and non-tuberculous mycobacteria (NTM). Methods A total of 11 standard strains including MTB H37Rv and 10 NTM standard strains were all from the National Tuberculosis Reference Laboratory. And 238 clinical isolates were frozen positive strains cultured from outpatients of Beijing Research Institute for Tuberculosis Control from January to December 2019, all of them were positive in acid fast smear staining. Eleven standard strains and 238 clinical isolates were identified by PNB/TCH growth test, MPB64 detection, PCR-fluorescent probe method and gene chip technology. Based on the identification results of microarray gene chip method, the efficiency of PNB/TCH growth test, MPB64 detection method and PCR-fluorescent probe method to identify MTBC and NTM was evaluated. Results Compared to strain identification with gene chip technology, the sensitivities of PNB/TCH growth test, MPB64 detection and PCR-fluorescent probe method were 100.0% (206/206), 98.5% (203/206) and 100.0% (206/206), respectively; the specificities were 96.9% (31/32), 100.0% (32/32), 100.0% (32/32). The coincidence rates were 99.6% (237/238), 98.7% (235/238) and 100.0% (238/238), respectively; the Kappa values were 0.98, 0.95 and 1.00, respectively. The detection times of PNB/TCH growth test, MPB64 detection method and PCR-fluorescent probe method were 28 days, half an hour, and half of the day, respectively; the average detection costs were RMB 20 yuan, 40 yuan and 60 yuan. Both PNB/TCH growth test method and MPB64 detection method need cultures, while PCR-fluorescent probe method requires laboratories and operators with professional ability of nucleic acid detection. Conclusion PNB/TCH growth test, MPB64 detection and PCR-fluorescent probe method could be used to identify MTBC and NTM. PCR-fluorescent probe method has high sensitivity and specificity, and the detection results are more accurate and reliable. MPB64 detection is simple, rapid and with low cost, it is suitable for the preliminary identification in primary laboratories.

Key words: Mycobacterium tuberculosis, Mycobacteria,atypical, Diagnosis,differential, Laboratory techniques and procedures, Evaluation studies