Invasive bacterial infections are a major complication in cancer patients and they remain one of the leading causes of morbidity and mortality. Among them, bloodstream infections (BSI) caused by vancomycin-resistant enterococci (VRE) have emerged as one most important complications of cancer therapy in patients with hematological malignancies. Previous gastrointestinal (GI) colonization is a well-known risk factor for VRE BSI, however, only a subset of Gl colonized patients develop invasive disease. The factors determining this balance between colonization vs. invasion are unknown. Moreover, there is important regional variance in the incidence of VRE BSI in cancer patients, despite similar colonization rates. In addition, the clinical presentation of patients with VRE BSI also varies, with some of them presenting with a mild infection, while others develop a prolonged and difficult-to-manage infection.