Prophylaxis with levofloxacin: bacterial infections and antimicrobial resistance in hematological malignancies*

Studies evaluating bacterial prophylaxis of patients under high risk for the development of febrile neutropenia have been published since the 1980s.1-3 Initially, trimethoprim with sulfamethoxazole was used, but this is associated with an unacceptable risk of myelosuppression. Thus, fluoroquinolones became the treatment of choice worldwide, due to their good oral tolerability, broad antimicrobial spectrum, bactericidal activity, ability to preserve anaerobic gut microorganisms, and lack of myelotoxicity. Ciprofloxacin was initially used in this scenario, but the need to treat Streptococcus viridans led to a progressive trend to prescribing levofloxacin due to its better activity against this microorganism.4 Recent studies suggest that antibacterial prophylaxis with levofloxacin should be started when a neutropenia episode, secondary to chemotherapy, is expected. Decreasing rates of febrile neutropenic episodes and even all-cause mortality have been correlated with this approach.3,5,6 However, two aspects of this widely practiced procedure remain controversial and under discussion. First, it appears that the greatest benefit of antibiotic prophylaxis is restricted to patients who are expected to develop long and severe episodes of neutropenia (longer than seven days with neutrophils < 100 × 109 cells/L).7,8 Second, increasing rates of fluoroquinolone resistance in this group of patients have been described in the medical literature, including in hematological services where this routine was adopted. The widespread use of antimicrobials in incorrectly selected patient populations and the rise in bacterial resistance to these drugs exemplify a well-known phenomenon in the field of antimicrobial therapy. Indeed, the massive use of Scientific comment