A Study Of Phage Amplified Biologically Assay For The Detection Of Isoniazid And Rifampicin Resistance Of Mycobacterium Tuberculosis In Sputum

0bjective:To set up a fast,sensitive and specific way to detect drug susceptibility of isoniazid(INH)and rifampicin(RFP)of mycobacterium tuberculosis(MTB) in sputum by using phage amplified biologically (PhaB) assay.Methods:To detect the INH and RFP resistance of MTB in sputum by PhaB assay comparing the results of PhaB assay with that of absolute concentration method.Results:22 cases with INH-resistant and 11 cases with INH-sensitive sputum speci- mens were found in the total of 40 sputum specimens by the two methods.The test resuts were different in 7 cases of the 40 sputum specimens.The sensitivity,speci- ficity,positive and negative predictive values as well as overall accuracy for the PhaB assay were 78.57﹪,91.67﹪,95.65﹪,64.71﹪,82.50﹪respectively when using absolute concentration method as control.The kappa test result,k=0.63 P=0.00<0.05,which indicated two methods detecting results had fairly good compatibility.25 cases with RFP-resistant and 7 cases with RFP-sensitive sputum specimens were found in the total of 40 sputum spe- cimens by both of the methods.The test resuts were different in 8 cases of the 40 sputum specimens.The sensitivity,specificity,positive and negative predictive values and overall accuracy for the PhaB assay were 78.13﹪,87.50﹪,96.15﹪,50.00﹪,80.0﹪respectively if the judgement standard was adopted by absolute con- centration method.The kappa test result,k=0.51 P=0.00<0.05, which indicateed two methods detecting results had fairly good compatibility.The sensitivity,specificity,positive and negative predictive values and overall accuracy for the PhaB assay of INH and RFP resistance in 40 sputum specim- ens was not different(P>0.05).Conclusion:The PhaB assay can be used for rapid detection INH and RFP resistance of MTB in sputum with high sensitivity,specificity ,overall accuracy and good com- patibility with absolute concentration method within three days;it is easy to perform,requires no specialized equipment,needs low cost.The sensitivity,specificity,posi- tive and negative predictive values and overall accuracy for the PhaB assay is the same in rapid screening for different drugs resistance in MTB of sputum.