Objective      To study the correlation of gene MTB73 to drug resistant tuberculosis (TB) in children by measuring MTB73 mRNA expression in isolated strains of Mycobacterium tuberculosis (M.tuberculosis) resistant isolates. Methods      A total of 110 clinical isolates of children with TB were divided into resistant group and sensitive group by drug susceptibility test. Reverse transcriptase polymerase chain reaction (RT-PCR) and gene sequencing techniques were used to detect and verify MTB73 gene expression in the 110 clinical isolates. The expression level of MTB73 was quantified using SYBR Green I real-time PCR and the differences of the expression between these 2 groups were analyzed.  Results     Of 110 clinical isolates

11.82% (13 isolates) were MTB73 expressed. The expression rate and level of MTB73 were significantly higher in drug resistant isolates than in drug sensitive isolates

with statistical significance (Chi-square=6.014，P=0.014；t’=8.075，P0.001). The drug resistant isolates were further divided into 3 subgroups: single drug-resistance (n=32)

polyresistance (n=12) and multidrug resistance (n=14). The expression rate of MTB73 in multidrug resistant isolates（9，64.29%）was significantly higher than in single drug-resistant group（1，3.13%）

polyresistant group（1，8.33%）and drug sensitive group（2，3.85%）

with a statistically significant difference (Chi-square=17.969

P0.001; P=0.005; Chi-square=24.823

P0.001). Additionally

MTB73 expression was not significantly different among the single drugresistant

polyresistant and drug sensitive groups (P0.008). Conclusion     Gene MTB73 is significantly upregulated in resistant isolates

especially in multidrug resistant isolates

suggesting that MTB73 may be associated with drug resistance of children TB.