ORIGINAL ARTICLE The impact of antimicrobial prophylaxis in morbidity and infections during azacitidine treatment Natalia Lorenzana 1 & Laura Francisca Avila 1 & Sara Alonso 1 & Enrique Colado 1 & Teresa Bernal 1,2 Received: 29 May 2017 /Accepted: 3 August 2017 # Springer-Verlag GmbH Germany 2017 Abstract The clinical consequences of the infectious events in patients receiving azacitidine are poorly documented. Likewise, the role of primary antimicrobial prophylaxis is unknown. In this retrospective, single-center study, we compare the impact of pro- phylaxis on the incidence of infection and morbidity in all con- secutive higher-risk myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) patients, during the first 4 azacitidine cycles. Seventy-six patients, corresponding to 283 azacitidine cycles, were studied. There were infectious events in 43% of the patients. Development of infections led to more hospital ad- missions, increased red blood cells and platelet requirements, and a delay in subsequent cycles. Median overall survival was com- parable between patients with or without infections. In the mul- tivariate analysis, a neutrophil count below 0.5 × 10 9 /L (OR 12.5 [2.6–50]) and antimicrobial prophylaxis (OR 0.1 [0.02–04]) were independent factors for the development of infection. We con- clude that infectious events have a significant impact in the early clinical course of azacitidine-treated patients by increasing hos- pital admissions and transfusion requirements. Antimicrobial prophylaxis may prevent infections, leading to a decreased need for supportive care in these patients with poor outcome. Keywords Myelodysplastic syndrome . Acute myeloid leukemia . Azacitidine . Antimicrobial prophylaxis . Febrile neutropenia Azacitidine is currently considered the standard of care for patients with higher-risk myelodysplastic syndrome (MDS) who are not candidates for allogeneic stem cell transplantation in relation to their age or comorbidities. Based on a recent randomized trial [1], this drug has been also approved for treatment of patients with acute myeloid leukemia (AML) with more than 30% blasts in bone marrow and age above 65 years. Additionally, it can also be used as a debulking therapy before allogeneic stem cell transplantation [2]. Compared to intensive chemotherapy, this drug offers a better safety profile [3, 4], mainly due to a lower risk of infectious complications, especially after the first cycles of treatment. However, data regarding infection rates and their impact are scarce and have yielded heterogeneous results. Antimicrobial prophylaxis is only indicated for patients undergoing intensive chemotherapy and/or allogeneic stem cell transplantation, as it is the only case where it has been unequivocally demonstrated to improve survival [ 5 ]. However, this level of evidence has not been determined for higher-risk MDS patients treated with the hypomethylating agents because of several reasons: the number of published studies is low and its nature is highly variable, most of them are retrospective studies whose data are limited to the clinical characteristics of the infectious events; the overall incidence of infection in them varies greatly; likewise, the mortality attributable to infection in these patients is unknown, since the figures are often biased due to the inclusion and mixing of patients with different outcomes. Consequently, there is no clinical evidence to establish a pattern of antimicrobial pro- phylaxis in this subgroup [6] and therefore, clinical practice varies according to the centers. The main objective of this work is to evaluate the incidence, morbidity, and mortality of infectious events in patients with MDS or AML who receive azacitidine as first line of treatment, focusing on the impact of antimicrobial prophylaxis. * Teresa Bernal Teresa.bernal@sespa.es 1 Servicio de Hematología y Hemoterapia, Hospital Universitario Central de Asturias, Oviedo, Spain 2 Departamento de Medicina, Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, Oviedo, Spain Ann Hematol DOI 10.1007/s00277-017-3091-x