The main considerations for sputum mycobacterial culture or sputum common bacterial culture are as follows: 1. Patients should keep qualified sputum specimens. From the naked eye, for example, in terms of mycobacterial culture, it is usually considered that cheese like sputum, blood sputum and mucus sputum are qualified specimens and saliva is unqualified sputum specimens. 2. When doing sputum culture, it may be normal if the report form suggests specimen contamination. Because sputum contains many bacteria, Mycobacterium tuberculosis culture needs to kill or inhibit the growth of other miscellaneous bacteria, and let Mycobacterium tuberculosis alone. The process is called pre-treatment. The pre-treatment time is too long to affect the viability of Mycobacterium tuberculosis, and too short to cause contamination. Therefore, from the laboratory’s point of view and from the methodological point of view, an optimal pretreatment time is chosen to ensure maximum viability of Mycobacterium and maximum inhibition or killing of the mycobacteria, so the laboratory allows a certain contamination rate. When the patient gets a report card indicating specimen contamination, it is normal.3. Because the culture medium inoculated by each laboratory is different, the time of report issuance is also different, and the percentage of positive detection is also different, usually the culture of Mycobacterium tuberculosis, the report feedback time is much longer than that of ordinary bacterial culture. Normal bacterial culture may be informed of pathogenic or normal flora in 2-3 days, but Mycobacterium tuberculosis culture takes 8 weeks to issue a negative report if it is on solid medium, and 6 weeks to issue a negative report if it is on liquid medium, which is a longer time. Also for Mycobacterium tuberculosis culture, the report can only make the judgment of positive or negative Mycobacterium tuberculosis culture, and can not distinguish between Mycobacterium tuberculosis complex and non-tuberculous mycobacteria, that is, NTM, which requires further strain identification. Two methods are commonly used for strain identification, the solid medium method, called PNB/TCH growth test, which takes 4 weeks. The other method is the immunological identification test for the culture of Mycobacterium tuberculosis secretory protein MPB64, and if it is NTM (non-tuberculous mycobacteria), further strain identification is required, so it will take longer.