Background: Fluoroquinolone (FQ) prophylaxis is commonly used in patients with neutropenia. Here, we describe trends in FQ susceptibility over time at a large tertiary care cancer center.
Methods: E. coli susceptibility data on the first positive blood culture per patient from 2000-2013 were obtained. Cases were defined as patients with hematologic malignancies (HM) and/or hematopoietic stem cell transplant (HSCT). FQ prophylaxis was used for patients undergoing HSCT and patients with HM likely to develop grade 4 neutropenia (ANC < 0.5 x 109/L). Controls were patients with E. coli bloodstream infection (BSI) during the same time period without HM or HSCT. E. coli was considered FQ non-susceptible, if in vitro testing revealed non-susceptibility to any FQ. FQ interpretative breakpoints did not change during the study period. Rates of FQ non-susceptibility were compared between cases and controls. In case patients, time to all-cause mortality in 30 days and 1 year after first positive culture were compared based on FQ susceptibility using Kaplan-Meier curves.
Results: 1197 controls and 122 cases (88 HM patients and 34 HSCT recipients) with E. coli BSI were identified. Underlying malignancies included acute myeloid leukemia (42), acute lymphocytic leukemia (13), chronic leukemia (10), lymphoma (41), and others (16). The FQ non-susceptibility rate in control patients was 368/1197 (30.7%). In comparison, 31/88 (35.2%, p=NS) of HM patients and 29/34 (85.3%, p<0.001) of HSCT patients had FQ non-susceptible E. coli, respectively. Trends over time were compared (Figure 1). A rise in FQ non-susceptibility was observed in cases starting in 2004. After 2007, rates have stabilized between ~40-70%. Of interest, FQ non-susceptibility rates in controls have also risen and are now stable around 40%. Whereas no difference in 30-day mortality was observed, 1-year mortality was higher in cases with FQ non-susceptible E. coli when compared to cases with FQ susceptible E. coli (Figures 2 and 3).
Conclusion: FQ resistance in E. coli BSI has increased over the last decade in both cases and controls, especially in the HSCT population. This calls into question the efficacy of universal FQ prophylaxis for high-risk cancer patients with expected prolonged and profound neutropenia.
C. G. Hauck,
M. Miller, None
K. J. Jamieson, None
T. Shea, None
M. Foster, None
D. Van Duin, Sanofi-Pasteur: Consultant , Consulting fee
Scynexis: Investigator , Research support
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