Clinical impact of fluoroquinolone prophylaxis in neutropenic patients with hematological malignancies

The routine use of fluoroquinolone prophylaxis in patients with neutropenia and hematological malignancies is controversial. This prophylaxis has been reported to have a positive impact in reducing infection-related mortality, but the consequent development of antibiotic resistance has become a concern. This study assessed the effect of discontinuing quinolone prophylaxis on the etiology and the resistance pattern of blood culture isolates and on the prognosis among febrile neutropenic patients receiving chemotherapy.The results of blood cultures obtained from febrile neutropenic patients between January 2003 and June 2009 were analyzed; these results were available through a computer database set up in 2003.Patients receiving quinolone prophylaxis between 2003 and 2005 showed a lower incidence of Gram-negative bacteria than patients not receiving prophylaxis between 2006 and 2009 (13.5%, n=9 vs. 48.1%, n=75). Interestingly, after discontinuing prophylaxis, approximately 70% of the Gram-negative bacteria isolated were quinolone-resistant, and some were extended-spectrum β-lactamase (ESBL) producers. The frequencies of quinolone-resistant Gram-positive bacteria isolated were similar between the period of quinolone prophylaxis and the period with no prophylaxis (61.1% vs. 64.3%). In both periods, all Gram-positive isolates were sensitive to vancomycin. The infection-related mortality was comparable between patients receiving prophylaxis and those not receiving prophylaxis (1.5%, n=1 vs. 1.3%, n=2).These findings suggest that quinolone prophylaxis for neutropenia does not induce a significant increase in the growth of quinolone- and multidrug-resistant bacteria. Rather, discontinuing quinolone prophylaxis may induce a dramatic increase in the growth of Gram-negative bacteria, including ESBL producers. Our results suggest that the necessity for quinolone prophylaxis in neutropenic patients should be determined based on local antibiotic resistance patterns.