Abstract:

Objective To explore the drug resistance spectrum of Mycobacterium tuberculosis isolated from the drug-resistance surveillance sites in Hu’nan Province from 2014 to 2018, and to analyze the change trend of drug resistance. Methods A total of 1463 strains of Mycobacterium tuberculosis complex were isolated from sputum smear-positive tuberculosis cases registered in 5 national tuberculosis drug resistance monitoring sites in Hu’nan Province from 2014 to 2018. Drug sensitivity test was carried out on Mycobacterium tuberculosis complex strains. The tested drugs included isoniazid (INH), rifampicin (RFP), ethambutol (EMB), streptomycin (Sm), kanamycin (Km) and ofloxacin (Ofx). The drug resistance spectrum of the strains was described and the changes of characteristics of drug resistance were analyzed. Results Among the 1463 strains, 1244 (85.0%) were isolated from new tuberculosis patients and 219 (15.0%) were isolated from retreated tuberculosis patients. A total of 252 strains were resistant to at least one drug, and the rate of total drug resistance was 17.2% (252/1463), the rate of mono-drug resistance was 9.0% (131/1463), the rate of multi-drug resistance was 5.1% (74/1463) and the poly-drug resistance rate was 3.2% (47/1463). The drug resistance spectrum of the six anti-tuberculosis drugs consisted of 30 different types of drug resistance. Resistance rate of the six drugs were INH 9.9% (145/1463), Sm 8.2% (120/1463), RFP 7.0% (103/1463), Ofx 5.2% (76/1463), EMB 2.3% (34/1463) and Km 0.8% (12/1463), respectively, the difference was statistically significant (χ²=318.838, P=0.001). From 2014 to 2018, the drug resistance rates of isolates to RFP were 48.4% (15/31), 45.3% (34/75), 40.0% (20/50), 46.3% (19/41), and 27.3% (15/55), respectively, showing a downward trend ( {\chi }_{\mathrm{trend}}^2 =7.028, P=0.008); the drug resistance rates were 15.7% (31/198), 20.2% (75/371), 21.5% (50/233), 17.3% (41/237) and 13.0% (55/424), respectively, which also showed a downward trend ( {\chi }_{\mathrm{trend}}^2 =3.850, P<0.05). The drug resistance rate and multi-drug resistance rate in strains isolated from retreatment tuberculosis cases were significantly higher than those of the strains isolated from new tuberculosis cases (28.8% (63/219) vs. 15.2% (189/1244), χ²=24.065, P<0.01; 12.8% (28/219) vs. 3.7% (46/1244), χ²=32.024, P<0.01). Conclusion The drug resistance of Mycobacterium tuberculosis in Hu’nan Province was at a medium level and the drug resistance rate showed a decreasing trend year by year. The rates of drug resistance and multi-drug resistance in the re-treated patients were higher than those in the newly treated patients.

Key words: Mycobacterium tuberculosis, Drug resistance, Population surveillance