Abstract: Objective evaluate the clinical value of thin-layer agar (TLA+PNB) on the diagnosis of TB and identification of mycobacterial species.  Methods 211 samples including sputum and extra-pulmonary specimens from suspects with a clinical diagnosis of TB were decontaminated using NaOH/NALC, centrifuged, and then stained with Ziehl-Neelsen for the detection of acid-fast bacilli (AFB), cultured on L-J medium and TLA+PNB medium and identified by 16S rDNA sequencing. Sensitivity and specificity, growth detection time and contamination rate were calculated for both media.  Results Of AFB-positive samples, 77.4% were culture positive. Of AFB-negative samples, 8.2% were both L-J and TLA culture positive. The sensitivity and specificity of both L-J and TLA culture were 84.2% and 100%, respectively. 8 non-tuberculosis mycobacteria of 48 cuture-positive samples were detected by TLA+PNB, in which the sensitivity and specificity were 88.9% and 100%, respectively. Contamination rates were 4.7% for TLA and 1.2% for L-J. Median time of a positive culture was 10.6 days for TLA and 22.9 days for L-J (P<0.001).  Conclusions The TLA+PNB method is an inexpensive, rapid and reliable alternative for detectingM. tuberculosis .

Key words: Mycobactorium tuberculosis, baeteriological techniques, gels, evaluation studies