Gut Colonization with Carbapenem-resistant Enterobacteriaceae Adversely Impacts the Outcome in Patients with Hematological Malignancies: Results of A Prospective Surveillance Study

Background: Gut colonisation with carbapenem-resistant enterobacteriaceae (CRE) is a risk factor for CRE bacteremia and patients with haematological malignancies (HM) are at the highest risk of mortality. Methods: We conducted a prospective surveillance study of gut colonisation with CRE and its impact on the outcome of 225 consecutive patients of HM over 28 months. Results: The median age of the cohort was 46 years, the majority with acute leukaemia. 48 (21%) patients were colonised with CRE on admission (CAD). Another 46 patients were colonised with CRE in the hospital (CIH). The risk factors for CAD and CIH were a diagnosis of acute leukaemia and duration of hospital stay respectively. CRE accounted for 77% of infection-related mortality (IRM). The incidence of CRE bacteremia in CRE positive patients was 18% (17/94), and mortality in those with CRE bacteremia was 100%. IRM was 35.3% in CIH group compared to 10.5% in the CAD group (p=0.0001). IRM was highest in those with acute myeloid leukaemia (AML) and CIH (54.9% p=0.0001). On multivariate analysis, CIH was the most important risk factor for IRM (HR-7.2). Conclusion: Our data demonstrate that a substantial proportion of patients with HM are colonised with CRE without prior hospitalisation, but those with nosocomial colonisation have the highest risk of mortality, particularly in those with AML.