Objective: To determine the resistance rates of clinical isolates from patients of 13 hospitals located in different areas
of China. Methods: A total of 2 554 clinical isolates collected from 13 hospitals. Bacterial susceptibility testing was done by agar dilution method. Results were assessed according to NCCLS (2001). Results:Of 2 554 strains, 958 (37. 5%) were Gram-positive cocci and 1 596(62. 5%) were Gram-negative bacilli. Moxifloxacin and gatifloxacin were more active against Gram-positive cocci than the other
fluoroquinolones tested (P<0. 05). Moxifloxacin and gatifloxacin also had good
antibacterial activities against Gram-negative bacilli. Among all the fluoroquinolones tested, levofloxacin had the lowest resistance rates on Acineto-bacter spp. and Pseudomonas aeruginosa. Conclusions: Moxifloxacin and gatifloxacin have higher antibacterial activities against Gram-positive cocci than the other fluoroquinolones, while reserving good antibacterial activities against Gram-negative bacilli. Rational use of antimicrobials is most important for the containment of bacterial resistance.