Abstract: Objective To study the optimal experiment protocol,time of pyrazinamide susceptibility testing by phage-based splitting assay and its clinical applications.Result Middlebrook 7H9 acid liquid culture medium containing was added 0.4% sodium pyruvate as control.The numbers of plaques in the blank tubes and the optimal pyrazinamide action time of PhaB group and control group were observed.The drug susceptibility testing dilution method was used as control,pyrazinamide susceptibility testing by phage-based splitting assay and PhaB method were performed in 86 Mycobacterium tuberculosis isolates.Result The blank tubes in the control group and PhaB group formed 71 and 53 plaques,repectively.The agreement rates between the dilution method and new method were 90.7% and 87.2% after one day and two days of pyrazinamide action on the isolates,respectively.The agreement rate between the dilution method and PhaB method was 88.4%.Conclusions Based on PhaB,Middlebrook 7H9 acid culture medium containing sodium pyruvate could improve the accuracy of the test and shorten the action time between pyrazinamide and Mycobacterium tuberculosis.

Key words: PhaB, Culture medium,Sodium pyruvate, Pyrazinamide