Study on application of secretory protein MPB64 for identification of Mycobacterium tuberculosis complex

Abstract

Objective To evaluate the application of detecting secretory protein MPB64 for the identification of Mycobacterium tuberculosis complex.Methods For clinical isolated strains,0.1 ml of either liquid medium obtained from BacT/ALERT 3D system or bacterial sodium suspension from colonies cultured by L(o)wenstein-Jensen solid medium with 1 Mcfarland standard at room temperature for about two hours was made as samples.Secretory protein MPB64 was detected by immunochromatographic method with colloidal gold labeled anti-MPB64 monoclonal antibody,then the results were compared with the strain identification.For reference strains,both liquid culture medium and bacterial sodium suspension were detected.Results Totally,23 reference strains and 267 clinical isolated strains of mycobacteria were detected.① For the reference strains,Mycobacterium tuberculosis,Mycobacterium bovis and Mycobacterium microti were positive in two kind of samples,and other 20 non tuberculous Mycobacterium were negative.The accuracy of identification was 100 ％.②Among 111 clinical isolated strains from BacT/ALERT 3D system,55 strains were Mycobacterium,in which MPB64 of 51 strains was positive,and 56 strains were non'tuberculous Mycobacterium,in which MPB64 of 54 strains was negative.The accuracy of identification was 94.59 ％.③ Among 156 clinical isolated strains from L(o)wenstein-Jensen solid medium,121 strains were Mycobacterium tuberculosis,in which MPB64 of 115 strains was positive,and 35 strains were non tuberculous Mycobacterium,in which MPB64 was all negative.The accuracy of identification was 96.15 ％.④For all samples,the sensitivity,specificity and accuracy in the identification of Mycobacterium tuberculosis complex by detecting secretory protein MPB64 were 94.41％,98.20％ and 95.86％,respectively.Conclusions Identifying Mycobacterium tuberculosis complex by detecting secretory protein MPB64 was a accurate,fast and simple method.Furthermore,it could be widely used in clinic because of no special instrument. Key words: MPB64; Secretory protein; Mycobacterium tuberculosis complex; Bacterial typing technique