Benchmarking the in vitro activity of moxifloxacin against recent isolatesof Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae. A European multi-centre study

To benchmark the activity of moxifloxacin, a European study comprising 900 Streptococcus pneumoniae, 1051 Haemophilus influenzae, and 226 Moraxella ca tarrhalis referred from 30 institutions during 1998 is described. For S. pn eumoniae, moxifloxacin and trovafloxacin MIC90 and modal MICs values were 0 .12 mu g/ml and independent of susceptibility to other drug classes, geogra phy, or site of infection. MIC90/modal MICs were, respectively, 0.25/0.12 m u g/ml for grepafloxacin, 0.25/0.25 mu g/ml for sparfloxacin, and 1.0/0.5 m u g/ml for levofloxacin. The moxifloxacin C-max:MIC ratio of 20.8-26.3 is h igher than comparator fluoroquinolones. Five isolates were intermediate or resistant to grepafloxacin, sparfloxacin, or levofloxacin of which four and three remained susceptible to trovafloxacin and moxifloxacin, respectively . For moxifloxacin, > 90% of S. pneumoniae isolates demonstrated MICs great er than or equal to 3 dilutions below the susceptibility breakpoint used. M odal MICs and MIC90 for M. catarrhalis (both 0.03 mu g/ml) and H. influenza e (0.03 mu g/ml and 0.06 mu g/ml) were independent of beta-lactamase produc tion. These data demonstrate the in vitro activity of moxifloxacin and esta blish a baseline for future surveillance studies that will be important for detecting and tracking any trends in changing activity of this fluoroquino lone. (C) 2000 Elsevier Science Inc. All rights reserved.