Abstract: Objective  To study the value of the morphological characteristic with colloidal gold method in rapid identification of mycobacterial species.  Methods  A total of 853 clinical isolates of Mycobacteria were identified using morphological characteristic and colloidal gold method, and the results were compared with traditional experimental methods.  Results  The sensitivity and specificity of mycobacterial species identification by morphological characteristic were respectively 98.4%(750/762) and 96.7%(88/91). The sensitivity and specificity of identification by colloidal gold method were respectively 99.0%(754/762) and 98.9%(90/91). When the smears of culture-positive samples showed serpentine cord morphology and the colliodal gold test was positive, the culture would be reported to contain  Mycobacterium tuberculosis complex, and it’s PPV was 100.0%(741/741). When the cord morphology and the colloidal gold method test were all negative, the culture would be reported to contain non-tuberculous mycobacteria, and it’s NPV is 100.0% (87/87).  Conclusion  The morphological characteristic with colloidal gold method for the dentification of Mycobacterium tuberculosis complex could improve detection accuracy,  was a fast, easy method and suitable for all levels of laboratory.

Key words: Mycobacterium tuberculosis, Mycobacteria atypical, Gold colloid, Bacteriological techniques, Sensitivity and specificity