Study of fluoroquinolones resistance in rifampicin-resistant tuberculosis patients in Beijing: Characteristics, trends, and treatment outcomes.

BACKGROUND: China is a high-burden country for multidrug-resistant tuberculosis/rifampin-resistant tuberculosis (MDR/RR-TB). Fluoroquinolones (FQs) are key drugs for the treatment of patients with MDR/RR-TB. However, research on the resistance of FQs in Beijing is limited.

METHODS: We collected clinical isolates from all patients with pulmonary TB in Beijing from January 2016 to December 2021, conducted drug-sensitivity tests and sequencing for levofloxacin (LFX) and moxifloxacin (MFX), and collected the treatment plans and outcomes of the patients.

RESULTS: A total of 8512 clinical isolates were collected from patients with pulmonary TB, and 261 RR-TB strains were screened. The proportions of drug-sensitive and drug-resistant strains significantly differed by age group and treatment history. The rates of LFX and MFX resistance were 27.6% (72/261) and 36.4% (95/261), respectively. The detection rates of MDR-TB and pre-extensively drug-resistant TB (pre-XDR-TB) were 73.2% (191/261) and 36.4% (95/261), respectively, and the trends were significant (χtrend = 9.995, p = 0.002; χtrend = 12.744, p = 0.026). Among the 261 RR-TB strains, 14.9% (24/261) were sensitive to LFX but resistant to MFX. Among the four patients with LFX-resistant TB who received LFX treatment failed in three patients(Fisher's exact test, p = 0.009). The common mutation sites were 94 and 90 in gyrA. A novel mutation Ala90Ser was discovered.

CONCLUSIONS: FQs resistance trends in RR-TB patients in Beijing are striking. Strains showed incomplete cross-resistance to LFX and MFX. Testing for FQs resistance and developing a reasonable treatment plan are recommended. Attention should be given to the changing trends in MDR-TB and pre-XDR-TB.