Comparative In Vitro Antimicrobial Activities of the Newly Synthesized Quinolone HSR-903, Sitafloxacin (DU-6859a), Gatifloxacin (AM-1155), and Levofloxacin against Mycobacterium tuberculosis and Mycobacterium avium Complex

We compared the in vitro antimycobacterial activity of a new fluoroquinolone, HSR-903, with strong activity against gram-positive cocci with those of levofloxacin (LVFX), sitafloxacin (STFX), and gatifloxacin (GFLX). The MICs of the quinolones for Mycobacterium tuberculosis and Mycobacterium avium complex were in the order STFX ≈ GFLX < LVFX ≦ HSR-903 and STFX ≦ GFLX ≦ HSR-903 ≦ LVFX, respectively. HSR-903 effectively eliminated intramacrophagial M. tuberculosis, as did LVFX, and exhibited bacteriostatic effects against M. tuberculosis replicating in type II alveolar cells.