Importance of neutropenia for development of invasive infections at various phases of treatment for hemato-oncological diseases in children

Introduction: Prolonged neutropenia in patients with acute myeloid leukemia (AML), relapsed acute lymphoblastic leukemia (r-ALL), myelodysplastic syndrome (MDS), and those receiving hematopoietic stem cell transplantation (HSCT), is a well-known risk factor for infectious complications. Few data are available about the incidence and etiology of infectious episodes during the total treatment period associated with a decreased immunity. Methods: Between January 2000 and December 2005 children diagnosed with AML, r-ALL, and MDS, and post-HSCT patients were included in the study. A retrospective review based on microbiological data was performed to describe the incidence and etiology of the infectious complications during the total treatment period. Results: One hundred and thirty disease-specific patient episodes were included. Forty-two percent of 184 microbiologically proven infectious episodes were diagnosed in patients receiving chemotherapy, and 58% occurred in HSCT patients. During neutropenia, 123 (67%) infectious episodes were diagnosed; of the isolated species 83% were bacterial, 6% fungal, and 11% viral. In the period without neutropenia, 61 (33%) infectious episodes were diagnosed, with 38% bacterial, 3% fungal, and 59% viral species isolated. Of the infectious episodes diagnosed in patients treated with an HSCT, 52% (n = 55) occurred in the post-engraftment period. In contrast, in patients treated with chemotherapy, 92% of the infectious episodes were diagnosed during neutropenia. Conclusion: The number of proven infectious episodes in post-HSCT patients was not influenced by the presence of neutropenia, while in patients receiving chemotherapy significantly lower numbers of proven infectious episodes were diagnosed outside the neutropenic period.