A risk mitigation strategy was implemented to determine if a higher prophylactic voriconazole dosage in patients with CYP2C19 rapid metabolizer neutropenic acute myeloid leukemia (AML) reduces the incidence of subtherapeutic trough concentrations. Patients with AML (n = 263) were preemptively genotyped for CYP2C19*2, *3, and *17 alleles as part of a single‐center prospective, interventional, quality improvement study. CYP2C19 rapid metabolizers (CYP2C19*1/*17) were recommended to receive interventional voriconazole 300 mg twice daily, ultrarapid metabolizers (CYP2C19*17/*17) were recommended to avoid voriconazole, and all others received the standard prophylactic dosage of 200 mg twice daily. In this real‐world setting, 202 patients (76.8%) were prescribed prophylactic voriconazole, and of these patients 176 (87.1%) received CYP2C19‐guided prophylactic dosing. Voriconazole trough concentrations were obtained for 41 of the 58 (70.7%) CYP2C19 rapid metabolizers prescribed prophylactic voriconazole. Interventional voriconazole resulted in higher plasma trough concentrations (median 2.7 μg/mL) compared with the standard prophylactic dosage (median 0.6 μg/mL; P = 0.001). Subtherapeutic concentrations were avoided in 83.8% of CYP2C19 rapid metabolizers receiving interventional dosage compared to 46.2% receiving standard dosage (P = 0.02). CYP2C19 genotyping to preemptively guide prophylactic voriconazole dosing is feasible and may be a potential strategy for reducing the risk of subtherapeutic trough concentrations that potentiate breakthrough fungal infections.

BackgroundAntimicrobial stewardship in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients remains underutilized in North America. European guidelines advise de-escalation of broad-spectrum therapy after 72 hours in select patients with neutropenic fever of unknown origin. This is not commonplace in the United States, as current guidelines recommend broad-spectrum therapy until neutrophil engraftment. If de-escalating after at least 5 days of broad-spectrum therapy and defervescence in neutropenic allo-HSCT recipients does not predispose them to recurrent fever or infection, the practice could afford several benefits.MethodsThe primary end point was rate of recurrent fever. Secondary outcomes included Clostridium difficile–associated infections, length of stay, intensive care unit (ICU) admission incidence, in-hospital mortality rate, need for re-escalation of therapy, rate of positive blood cultures for patients who had recurrent fevers, overall antimicrobial utilization from neutropenic fever onset, and pharmacoeconomic impact.ResultsA total of 120 patients were assessed in 2 groups as cohort 1 (n = 46), which received early de-escalation, and cohort 2 (n = 74), which did not. The primary end point met criteria for noninferiority, as 7 patients (15%) in cohort 1 had recurrent fever within the specified time frame compared with 14 (19%) in cohort 2 (90% CI, –0.0878 to 0.1629, P = .026). Patients in cohort 1 received significantly less gram-positive broad-spectrum antimicrobials, with trends toward lower use of broad-spectrum gram-negative agents and lower associated costs and no differences in length of stay, ICU admission incidence, need for re-escalation of therapy, rate of culture-positive bacteremia after de-escalation or discontinuation of broad-spectrum therapy, or in-hospital mortality rate.ConclusionsDe-escalating after at least 5 days of broad-spectrum therapy and defervescence did not appear to affect the rate of recurrent fever. This allowed for significant reductions in gram-positive broad-spectrum antimicrobial utilization, with trends toward lower use of broad-spectrum gram-negative agents and associated costs and no difference in clinical outcomes compared with those continuing such therapy until neutrophil engraftment.

Infection with Nocardia species in allogeneic HSCT recipients appears to be a late complication of transplantation and most commonly involves the lung. Two-thirds of the cohort received a MAC regimen and the majority of the patients were receiving steroids at the time of diagnosis. Most patients were not receiving TMP-SMX for PJP prophylaxis at the time of nocardiosis diagnosis, and TMP-SMX may therefore have a protective effect.

Fever is frequently seen in patients with cancer and can be associated with a variety of infectious and noninfectious causes. The utility of acute-phase reactants, such as erythrocyte sedimentation rate, C-reactive protein, and procalcitonin, along with a nonsteroidal anti-inflammatory drug challenge should be further evaluated as adjunct tools for the workup of fever in patients with cancer.