Prophylaxis Versus a Preemptive Approach for Invasive Aspergillosis
Difficulty in making an early diagnosis of invasive aspergillosis and consequent poor clinical outcome have led to prophylactic and preemptive management strategies in patients at high risk. Classic high-risk populations include patients with chemotherapy-induced prolonged neutropenia in the setting of acute leukemia and allogeneic hematopoietic stem cell recipients with graft-versus-host disease. Prophylactic mode involves antifungal administration throughout the “at risk” period to prevent infection; published studies with posaconazole and to a much lesser extent, itraconazole, are of promise. However, many drawbacks of these triazoles preclude their liberal use. A preemptive approach involves serial screening of patients with the fungal biomarker, serum Aspergillus galactomannan, to identify early infection; this strategy may be initiated at the onset of the high-risk period or when there are clinical features suggestive of infection. Limited data available with this strategy in the neutropenic population are somewhat encouraging. Clearly, more refined diagnostic tools, improved “quantification” of risk for invasive aspergillosis in different subsets of patients, and direct comparative studies of the two strategies in different settings are needed. At present, prophylaxis against invasive aspergillosis with mold-active azoles may be reserved for those at the highest risk; for those at intermediate risk, prophylaxis with a yeast-active drug combined with the preemptive screening strategy is prudent.