Impact of discontinuing routine fluoroquinolone prophylaxis in neutropenic allogeneic haematopoietic stem cell transplant recipients: an observational study.

Background: Uncertainty exists as to the role of fluoroquinolone (FQ) prophylaxis for patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT) in the era of rising antibiotic resistance.

Objectives: We aimed to evaluate rates of bloodstream infections (BSI), resistance patterns and outcomes of patients after discontinuing routine FQ prophylaxis administration.

Methods: All adult recipients of first HSCT from 2017 to 2020 were retrospectively included and classified according to time of HSCT as FQ group (HSCT January 2017-December 2018) or no FQ group (January 2019-December 2020). The primary outcome was Gram-negative (GN) BSI from day -7 to 30 days post-HSCT. The independent association between the study period and BSI was assessed using survival analysis, and adjusting for confounders.

Results: We included 254 patients, 130 (51%) and 124 (49%) in the FQ and no FQ groups, respectively. Compared to the FQ group, no FQ had significantly more GN BSI (21% versus 33%, P = 0.027) and the median time to first GN BSI was significantly shorter [4 (IQR 1-8) days versus 6 (1-10) days, P = 0.009]. Following adjustment, FQ prophylaxis remained associated with lower hazard for GN BSI (hazard ratio 0.57, 95% CI 0.34-0.93). Eighty-two GN BSI episodes had FQ susceptibility testing. More GN BSI episodes were FQ resistant in the FQ group (68.9% versus 41.6%, P = 0.021). No significant difference was found for 30-day mortality, time to first febrile neutropenia and time to first broad-spectrum antibiotics between the groups (P was not significant).

Conclusions: FQ prophylaxis is associated with fewer GN BSI in the early post-HSCT period even in high FQ resistance settings, with FQ resistance rates reaching >60% following prophylaxis.