Inclusion Criteria:

- Age >= 18

- Pre-admission (ATU, ITA) or inpatient status

- ANC <= 1500/mm^3

- Patients with acute myeloid or lymphoid leukemia who:

- are admitted with newly diagnosed disease and have not yet received induction
chemotherapy

- are admitted with neutropenic fever after receiving post-remission chemotherapy
or are admitted for post-remission chemotherapy

- Patients with chronic myeloid leukemia or a chronic lymphoid leukemia/disorder who
have received chemotherapy or other disease-specific treatment in the last 30 days
where the ANC of <=1500/mm3 is considered by the treating physician to be at least
possibly treatment-related

- An intravenous line or catheter (Hickman, port, portacath, or PICC line) must be in
place at the time of protocol participation/study start, but will not be inserted
solely for the purposes of the study.

- Whenever possible, patients will be consented and blood monitoring will be initiated
before the first dose of antibiotic, but if not possible, at no time will standard of
care measures will be delayed or interrupted for the purposes of study enrollment.

- Patients must be able to understand the nature of the study and give written informed
consent.