In vitro activity of moxifloxacin against common clinical bacterial isolates in Taiwan.

The in vitro antimicrobial activities of moxifloxacin were compared with 7 other antimicrobial agents. A total of 707 isolates of 11 common pathogenic bacteria were collected from the National Taiwan University Hospital; antimicrobial activities against these isolates were evaluated by minimum inhibitory concentration using an agar-dilution method. Most common pathogenic bacteria were susceptible to moxifloxacin, including methicillin-susceptible and -resistant Staphylococcus aureus, methicillin-susceptible and -resistant Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Burkholderia cepacia, Acinetobacter baumannii, and Stenotrophomonas maltophilia. For many of these bacterial species, moxifloxacin was the most active antimicrobial agent compared with the third- and fourth- generation cephalosporins, carbapenems, monobactam, and other quinolones. Some strains of methicillin-resistant S. aureus and methicillin-resistant S. epidermidis demonstrated very low levels of minimum inhibitory concentration for moxifloxacin, suggesting the potential application of the drug to treat some drug-resistant gram-positive bacterial infections. Moxifloxacin was less active against P. aeruginosa, but was more active against S. maltophilia when compared with other fluoroquinolones. In conclusion, moxifloxacin exhibits an increased potency against gram-positive bacteria as compared with other tested antimicrobial agents, while preserving excellent activity against gram-negative bacteria. The drug appears to be a promising agent expressing activity against a wide variety of bacteria in Taiwan.