Therapeutic Drug Monitoring for Linezolid in the Treatment of Rifampin-resistant Tuberculosis

Inclusion Criteria: * Adult male or female patient \> 18 years of age * Microbiological confirmation of rifampicin-resistant tuberculosis (e.g., phenotypic or genotypic drug susceptibility testing, GeneXpert MTB/RIF™). Participants may have resistance to additional medications as well - i.e., MDR and XDR TB - but must have resistance to at least rifampin * Initiated on a rifampicin-resistant tuberculosis (RR-TB) treatment regimen containing linezolid, no more than 14 days prior to randomization * HIV status is known and confirmed * Both HIV-positive and HIV-negative individuals are eligible * If an individual reports unknown HIV status, they must consent to HIV testing at time of enrollment to confirm status. If they decline to be tested, they are not eligible for the study Exclusion Criteria: * Severe medical condition with expected death in the next 7 days * Pregnant at time of screening * Initial linezolid dose \< 600mg daily * Severe form of extrapulmonary TB (i.e., meningitis, pericarditis, or osteomyelitis) * Unlikely to follow-up at Nkqubela Hospital based on location of residence