Impact of new regimens and drugs on rifampin-resistant tuberculosis management in Mexico

Objective To compare the former tuberculosis treatment regimen including one fluoroquinolone (ofloxacin, levofloxacin, or moxifloxacin) and a second-line injectable drug (amikacin, kanamycin, or capreomycin) plus three to five oral drugs (regimen 1) with the current regimen including the three WHO group A drugs (regimen 2) in terms of efficacy and safety at two tuberculosis referral centers in Mexico. Methods This was a retrospective study based on a review of the clinical records of all consecutive rifampin-resistant or multidrug-resistant tuberculosis (RR/MDR-TB) patients treated from January of 2010 to October of 2023. Patients included were microbiologically confirmed cases of RR/MDR-TB with pulmonary involvement and who received at least 30 days of regimen 1 or regimen 2. Outcomes and adverse events were classified in accordance with WHO definitions. Results One hundred and twenty-six RR/MDR-TB patients met the inclusion criteria. Of those, 87 were treated with regimen 1 and 39 received regimen 2. Success rates were not significantly different between the two groups of patients, although those treated with the oral regimen including bedaquiline from regimen 2 had higher success rates. Regimen 2 patients experienced a shorter time to culture conversion, and the regimen length was shortened accordingly, the median duration being 16.1 months [IQR, 15-17.3 months]. In patients receiving the all-oral regimen 2, adverse events were significantly associated with a history of type 2 diabetes mellitus (OR = 15.4; 95% CI, 2.73-87.29; p = 0.002) and were mainly related to linezolid use. Conclusions Oral regimens appear to be effective, although toxicity to linezolid requires strict patient monitoring.