Most strains of E. coli are not harmful but are part of the healthful bacterial flora in the human gut. Ingestion of these strains causes infection with symptoms including, but not limited to, severe stomach cramps, diarrhoea, fever and vomiting. In some cases, the bacteria can translocate from the gut to the bloodstream causing sepsis. In cancer patients with haematological malignancies, which are cancers that affect the blood, bone marrow, and lymph nodes, these infections causing sepsis are especially severe. These patients are at increased risk of life-threatening bloodstream infections as a result of their disease and chemotherapy treatment, rendering the patients immunologically compromised.