Infectious complications of patients undergoing therapy for acute leukemia: current status and future prospects

The success of managing the infectious complications of acute leukemia has permitted oncologists to develop new approaches to induction and high-dose therapy. The single most important risk factor for infection is the duration of absolute neutropenia. Historically, most attention was directed towards gram negative aerobes, especially Pseudomonas aeruginosa, but in recent years gram positive bacteria, generally considered to be less virulent, have become the most frequent isolates in most centers. A recent disturbing trend is the isolation of vancomycin-resistant enterococci. A recent controversy has been whether to use empirical vancomycin; the Centers for Disease Control has issued a formal recommendation discouraging empirical vancomycin in the febrile neutropenic patient. Empirical monotherapy has replaced combination therapy in many institutions except where there has been an increase in resistant isolates. In patients who remain profoundly neutropenic, fungal infections represent a serious source of secondary infection, especially species of Candida and Aspergillus. Recently lipid-based formulations of amphotericin B have offered reduced nephrotoxicity. Less toxic antifungals, the azoles, which include fluconazole and itraconazole, offer an attractive alternative to amphotericin B. New patterns of invasive mycoses have emerged, as for example hepatosplenic candidiasis, presenting new problems in diagnosis and therapy. The successful management of virus infections with herpes simplex, cytomegalovirus, varicella zoster, and Epstein Barr virus is based on early recognition and careful attention to prevention.