In vitro activity of domestic gatifloxacin and other antibacterial agents against common pathogens

Objective To investigate the In vitro activity of domestic gatifloxacin and some comparators against common pathogens.Methods Three hundred and seven isolates were collected from outpatients and inpatients at our hospital from September to December 2003. The minimum inhibitory concentrations (MIC) of gatifloxacin and other antibacterial agents for these 307 isolates were determined by agar dilution method according to National Committee for Clinical Laboratory Standards (NCCLS).Results Fluoroquinolones had good activity aginst Streptococcus pneumoniae (susceptibility rate, (93.5)%-100%). The activity of moxifloxacin was 2-4-fold higher than that of gatifloxacin, while the activity of gatifloxacin was 4-fold higher than that of levofloxacin. The activity of moxifloxacin and gatifloxain were not influenced by the resistance to penicillin and macrolides. All of the β-hemolytic Streptococci tested were susceptible to penicillin, cefuroxime and ceftriaxone. And the activity of 4 fluoroquinolones was in following order: gatifloxacin=moxifloxacinlevofloxacin=ciprofloxacin. All of MSSA isolates tested were susceptible to cephalosporins, gatifloxacin and moxifloxacin, and only 50% susceptible to azithromycin. Four fluoroquinolones had poor activity against Enterococcus spp. The prevalence of β-lactamases in Haemophilus influenzae and Moraxella catarrhalis was (12.9)% and (72.7)%, respectively. Cefuroxime, ceftriaxone, azithromycin and fluoroquinolones had good activity against these two species. Cefuroxime and ceftriaxone had no activity against ESBL-producing E.coli and Klebsiella pneumoniae. About 30% to 50% of ESBL-producing E.coli and Klebsiella pneumoniae were susceptible to the 4 fluoroquinolones tested. As for Pseudomonas aeruginosa, the activity of gatifloxacin and levofloxacin was one-fourth-fold of that of ciprofloxacin.Conclusions Domestic gatifloxacin had excellent activity against common pathogens from community-acquired respiratory tract infections and some activity against hospital-acquired pathogens.