Abstract:

Objective To analyze the drug resistance and types of phenotypic drug sensitivity test (phenotypic drug sensitivity test) of rifampicin-resistant Mycobacterium tuberculosis (MTB) isolates diagnosed by GeneXpert MTB/RIF (Xpert). Methods A retrospective study was conducted in which 346 rifampicin-resistant pulmonary tuberculosis (RR-PTB) patients (142 new cases and 204 re-treated cases) from the Third People’s Hospital of Shenzhen between January 2015 and December 2020. The drug resistance and types of phenotypic drug sensitivity test of clinical isolates of MTB strains to 10 anti-tuberculosis drugs (rifampicin, isoniazid, streptomycin, rifabutin, ethambutol, levofloxacin, p-aminosalicylic acid, amikacin, protionamide, capreomycin) were analyzed. Results The resistance rates of the 346 strains to 10 anti-tuberculosis drugs from high to low were rifampicin (95.95%, 332/346), isoniazid (84.68%, 293/346), streptomycin (58.38%, 202/346), rifabutin (57.23%, 198/346), ethambutol (50.29%, 174/346), levofloxacin (34.39%, 119/346), p-aminosalicylic acid (11.85%, 41/346), amikacin (10.69%, 37/346), protionamide (5.78%, 41/346) and capreomycin (5.20%,18/346). In the re-treated cases, the resistant rates to isoniazid, levofloxacin, ethambutol and amikacin were significantly higher than those in the new cases (88.24% (180/204) vs. 79.58% (113/142), χ ²=4.838, P=0.028; 40.69% (83/204) vs. 25.35% (36/142),χ ²=8.725, P<0.01; 55.39% (113/204) vs. 42.96% (61/142), χ ²=6.372, P=0.012; 13.73% (28/204) vs. 6.34% (9/142), χ ²=4.784, P=0.029, respectively). Analysis of drug resistance types showed that the multi-drug resistant (MDR) rate was 84.68% (293/346), the pre-extensive drug resistance rates (pre-XDR) of levofloxacin resistance and second-line injection resistance were 26.30% (91/346) and 5.20% (18/346), and the extensive drug resistance (XDR) rate was 6.65% (23/346). The MDR and pre-XDR rate in re-treated cases were significantly higher than those in the new cases (88.24% (180/204) vs. 79.58% (113/142), χ ²=4.147, P=0.042; 37.75% (77/204) vs.22.54% (32/142), χ ²=8.976, P<0.01), while the single resistance rate of rifampicin in the re-treated was significantly lower than that in the new cases (11.76% (24/204) vs. 20.42% (29/142),χ ²=4.838,P=0.028). Conclusion The rifampicin-resistant tuberculosis strains showed a higher rate of resistance to isoniazid and levofloxacin, especially in re-treated cases. It was necessary to detect resistance to isoniazid and fluoroquinolones as early as possible in rifampicin-resistant pulmonary tuberculosis patients, to optimize the treatment regimen.

Key words: Tuberculosis,pulmonary, Rifampicin, Tuberculosis,multidrug-resistant, Microbial sensitivity tests, Drug resistance characteristics