Utility of fosfomycin as antibacterial prophylaxis in patients with hematologic malignancies

Prolonged and profound neutropenia is common among hematology and hematopoietic stem cell transplant (HSCT) patients as a result of chemotherapy. The National Comprehensive Cancer Network (NCCN) and Infectious Diseases Society of America (IDSA) currently recommend antibacterial prophylaxis in patients who are deemed at intermediate or high risk for infection. Specifically, fluoroquinolone prophylaxis should be considered for high-risk neutropenic patients. However, with prolonged and frequent exposure to fluoroquinolones, these high-risk patients may develop resistance to these agents. Patients may also have allergies or other contraindications which prohibit the use of fluoroquinolones for antibacterial prophylaxis. Unfortunately, there is no standard recommendation for alternative antimicrobial therapy in this patient population, as well as there is a lack of data to support the use of potential alternative agents.

Currently, Yale-New Haven Hospital utilizes fosfomycin for antibacterial prophylaxis in patients who are not eligible for fluoroquinolone therapy. The primary objective of this study was to assess the incidence of breakthrough infections in this population receiving fosfomycin. Secondary objectives included organisms identified, types of breakthrough infections, resistance patterns, and time from initiation to onset of fever.

Of the 42 patients who received fosfomycin, 25 patients with 42 admissions met inclusion criteria. A total of 8 (19%) breakthrough infections occurred during the 42 admissions. Organisms included Klebsiella spp. (5), Streptococcus mitis/viridans (2), Pseudomonas aeruginosa (1), and coagulase-negative staphylococcus (1). Infections included the following: bacteremia (7), cellulitis (1), and urine (1).

Given the low rate of breakthrough infections, fosfomycin may be a potential alternative option for antibacterial prophylaxis.