Patients with hematological malignancies who receive intensive chemotherapy usually develop a period of cytopenia, during which there is an increased risk of infection. Mucositis can also develop in these patients, enabling micro-organisms, belonging to the endogenous intestinal flora, to translocate from the intestine to the lymphoid tissue and blood. Therefore, when mucositis and cytopenia develop simultaneously, the risk of infection increases further. In this regard bloodstream infection by Gram negative rods and yeasts are an important cause of serious infections causing considerable morbidity.