A significant increase in resistant bacteria emerging in HSCT recipients. For example, 25% - 42% of all enterobacteriaceae produce extended spectrum beta-lactamases; 8 - 72% of Pseudomonas aeruginosa are resistant to at least one and 25 - 62% to three or more antibiotic classes, 13% of Gram-negative bacteria are caused by a multidrug-resistant (MDR) strain (Trecarichi JI 09, Mikulska BBMT 09, Oliveira BMT 07, Caselli Haemat 10, Gudiol, JAC 11). These resistant bacteria may be associated with increased mortality and have limited treatment options (Caselli Haemat 10, Poutsiaka BMT 07, DiazGranadoz JID 05). To provide the currently best empirical coverage and to control the growing resistance, knowledge of trends in antibiotic susceptibility, as well as risk factors is essential. For this reason we propose to perform non-interventional prospective multicentre study in EBMT centres.