Abstract: Objective To develop a rapid method to detect Mycobacterium tuberculosis（MTB）resistance to ofloxacin by phage-amplified biologically (PhaB) assay, and to evaluate its clinical value.  Methods Compared with absolute concentration method, 205 MTB clinical isolates were detected their resistance to ofloxacin. If the Results from these two Methods are inconsistent, the ofloxacin susceptibility of this strain would be was determined by the proportion method.   Results As the Results from the absolute concentration method was considered as the golden standard, the sensitivity, specificity, positive and negative predictive value (PPV and NPV) as well as accuracy of PhaB assay for the ofloxacin susceptibility was 95.4%, 93.2%, 91.2%, 96.5% and 94.1%, respectively. The Results from 12 isolates were different between PhaB assay and the absolute concentration method, in which the Results from PhaB assay in 9 isolates were identical with that from the proportion method.  Conclusions The Results of ofloxacin susceptibility from PhaB assay had higher concordance with that from the absolute concentration method. PhaB assay can be used for rapid screening of drug susceptibility in MTB.

Key words: Mycobacterium tuberculosis, microbial susceptibility test, phenotype, Ofloxacin