linezolid + bedaquiline + cycloserine

This is a combination regimen of three small-molecule antibiotics—linezolid, bedaquiline, and cycloserine—used primarily for the treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. - **Linezolid** is an oxazolidinone antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, preventing formation of the initiation complex. It is effective against Mycobacterium tuberculosis but can cause hematologic and neurologic toxicities[4][6][9]. - **Bedaquiline** is a diarylquinoline that targets mycobacterial ATP synthase by binding to its oligomeric subunit C, thereby inhibiting ATP production essential for bacterial survival. It has both bacteriostatic and bactericidal effects against M. tuberculosis[2][3][4]. - **Cycloserine** is a broad-spectrum antibiotic that inhibits cell wall synthesis in mycobacteria by interfering with alanine racemase and D-alanine:D-alanine ligase activity; it has no known cross-resistance with other TB drugs but carries risk of CNS toxicity including depression, psychosis, or seizures[4]. This combination forms part of all-oral regimens recommended in international guidelines for MDR/XDR-TB when resistance or intolerance to first-line agents exists. The regimen may be tailored based on susceptibility testing and patient tolerance.