Discontinuing Ciprofloxacin Prophylaxis in Allogeneic Stem Cell Transplantation Does Not Result in Inferior Outcomes

The role of fluoroquinolone (FQ) prophylaxis during neutropenia after allogeneic stem cell transplantation (alloSCT) remains unclear due to concerns about antimicrobial resistance, microbiome disruption, and potential effects on graft-versus-host disease (GvHD). However, data comparing outcomes before and after FQ discontinuation remain limited. To compare the impact of discontinuing routine ciprofloxacin prophylaxis on bacterial bloodstream infections, GvHD, and overall survival in adult alloSCT recipients. In this retrospective single-center study, 292 adult alloSCT recipients were analyzed. Of these, 116 received ciprofloxacin prophylaxis during neutropenia and 176 did not, following an institutional policy change. Bacterial bloodstream infections (BSI), GvHD, and overall survival (OS) were analyzed. Overall BSI rates were similar between the FQ and non-FQ groups (42% versus 48%, P = .40). FQ prophylaxis shifted the pathogen spectrum of first BSI episodes toward gram-positive organisms (76% versus 36%, P < .001), while gram-negative and polymicrobial infections were more common without prophylaxis. Early mortality did not differ across BSI subtypes. Grade III-IV acute GvHD was numerically higher without FQ prophylaxis (36% versus 23%, P = .03) but did not persist as an independent association after multivariable adjustment for graft cryopreservation. In multivariable analysis, FQ prophylaxis was not independently associated with BSI (aOR 0.69, 95% CI 0.35 to 1.36, P = .28), grade III to IV acute GvHD (aOR 1.00, 95% CI 0.45 to 2.24, P = 1.00), or OS (HR 1.39, 95% CI 0.84 to 2.28, P = .20). Cryopreserved grafts were the strongest independent predictor of grade III-IV acute GvHD (aOR 3.49, 95% CI 1.80 to 6.78, P < .001). Discontinuation of ciprofloxacin prophylaxis was not associated with increased BSI rates, higher GvHD incidence, or inferior survival in this inpatient alloSCT cohort. FQ prophylaxis shifted the pathogen spectrum without conferring a measurable clinical benefit. These data are compatible with antibiotic stewardship strategies that forgo routine FQ prophylaxis in inpatient alloSCT settings with robust surveillance and prompt empiric therapy.