N. Yamane et al., LEVOFLOXACIN IN-VITRO ACTIVITY - RESULTS FROM AN INTERNATIONAL COMPARATIVE-STUDY WITH OFLOXACIN AND CIPROFLOXACIN, Journal of chemotherapy, 6(2), 1994, pp. 83-91
Levofloxacin, the S-(-)-isomer of ofloxacin, was compared to ofloxacin
and ciprofloxacin against > 6000 recent clinical isolates of Gram-pos
itive and Gram-negative bacteria from six different countries. This in
ternational multicenter study demonstrated a high level of antibacteri
al activity of levofloxacin against all the members of Enterobacteriac
eae [minimum inhibitory concentration (MIC)50s, less-than-or-equal-to
0.03 to 0.12 mg/L] except Providencia rettgeri (MIC50, 2 mg/L), and Pr
ovidencia stuartii (MIC50, 1 mg/L). Oxacillin-susceptible staphylococc
i (MIC50s, 0.12 to 0.25 mg/L), enterococci (MIC50s, 0.5 to 2 mg/L), an
d streptococci (MIC50s, 0.5 mg/L) were also susceptible to levofloxaci
n, but most isolates of oxacillin-resistant staphylococci had MICs of
greater-than-or-equal-to 4 mg/L. Levofloxacin was also active against
non-enteric Gram-negative bacilli, including Acinetobacter species (MI
C50s, less-than-or-equal-to 0.03 to 1 mg/L), Pseudomonas species (MIC5
0s, 0.5 to 1 mg/L) and Xanthomonas maltophilia (MIC50, 0.5 mg/L). Over
all, levofloxacin inhibited 50% and 90% of all the tested strains at t
he concentrations of 0.12 and 4 mg/L, respectively. The activity of le
vofloxacin was generally two-fold greater than ofloxacin and equal to
or slightly less potent than ciprofloxacin.