Comparative in vitro Activity of Levofloxacin and Ciprofloxacin against Bacterial Isolates from Neutropenic Patients

Background: Novel fluoroquinolones have been recently introduced in the management of neutropenic patients because of their increased activity against gram-positive and gram-negative micro-organisms. Methods: The activities of levofloxacin and ciprofloxacin were determined by the E test against 223 bacterial isolates from patients with haematological malignancies. Results: In general, the activity of levofloxacin was comparable to that of ciprofloxacin. Levofloxacin was somewhat more active against methicillin-resistant Staphylococcus aureus isolates. All methicillin-susceptible S. aureus isolates were inhibited by ciprofloxacin and levofloxacin at a concentration of ≤0.5 and ≤0.25 µg/ml, respectively. Among gram-negative isolates tested, levofloxacin was significantly (p < 0.001) more active than ciprofloxacin against Stenotrophomonas maltophilia, inhibiting 68 and 53% of these isolates, respectively. Conclusions: Levofloxacin was not superior to ciprofloxacin in its overall antibacterial activity, although small differences between these agents were seen depending on the species tested. In particular, our data suggested that levofloxacin may potentially be used for the management of S. maltophilia infections in neutropenic patients.