Objective To analyze and compare the mRNA expression levels of same sigma gene in different drug-resistant phenotypes of Mycobacterium tuberculosis.

Methods Retrospective analysis was conducted by using the rifampicin and isoniazid resistant strains, multidrug-resistant strains, and drug sensitive strains of M. tuberculosis collected in the outpatient department of Tianjin Tuberculosis Control Center from 2018 to 2022, the RNA of M. tuberculosis was extracted in log phase, and the mRNA expression levels of M. tuberculosis sigma factor (sigA-sigL) in each drug resistant group and drug sensitive group were detected by fluorescence quantitative polymerase chain reaction (RT-PCR), and the data were analyzed by mann-whitney U test, and χ² test was used to analyze the difference of gene high expression rate between the drug resistant groups and the drug sensitive group.

Results Except sigB, the expression levels of sigA-sigL in the isoniazid resistant group were significantly higher than those in the drug sensitive group (P<0.05); Except sigD and sigL, the expression levels of sigA-sigL in the rifampicin resistant group were significantly higher than those in the drug sensitive group, (P<0.05). The differences in expression levels of sigA, sigD, sigF, sigG, sigH, sigJ and sigK between the multi-drug resistant group (isoniazid drug-containing medium) and the drug sensitive group were significant (all P<0.05). Except sigD and sigI, the differences in expression levels of sigA-sigL between the multi-drug resistant group (rifampicin drug-containing medium) and the drug sensitive group\ were significant (all P<0.05). The high expression rates of sigG, sigI and sigJ in isoniazid resistant groups were significantly higher than those in the drug sensitive group, the differences were significant (χ²=32.676, 26.424, 21.171, all P<0.05). The high expression rate of sigJ in rifampicin-resistant group was significantly higher than that in the drug sensitive group, the difference was significant (χ²=21.171, P<0.05). The high expression rates of sigG, sigI and sigJ in the multi-drug resistant groups (isoniazid drug-containing medium) were significantly higher than those in the drug sensitive groups, with statistical significance (χ²=32.676, 26.424, 21.171, all P<0.05). The high level expression rate of sigJ in the multi-drug resistant groups (Rifampicin drug-containing medium) was significantly higher than that in the drug sensitive group, the difference was significant (χ²=21.171, P<0.05).

Conclusion The sigF, sigG and sigJ of M. tuberculosiswere associated with isoniazid and rifampicin resistances, indicated by their higher expression in the rifampicin resistant, isoniazid resistant and multi-drug resistant strains compared with the drug sensitive strains in this study.