Mortality burden related to infection with carbapenem-resistant Gram-negative bacteria among haematological cancer patients: a retrospective cohort study

Objectives: Carbapenem-resistant Gram-negative bacteria (CRGNB) pose a clinical challenge. We attempted to estimate the mortality burden of CRGNB among haematological cancer patients. Methods: This was a retrospective cohort study. We included adult patients hospitalized in the haemato-oncological/bone marrow transplantation departments for chemotherapy, between 2008 and 2014, with Gram-negative aerobic bacteraemia. We compared patients with CRGNB and carbapenem-susceptible Gram-negative bacteraemia (CSGNB). The primary outcome was 14 day all-cause mortality. In addition, we assessed 1 year survival. Multivariable logistics regression analysis and adjusted Cox regression analysis were conducted. Analyses were adjusted to the propensity for CRGNB bacteraemia. Results: The cohort included mostly young patients (mean age 50.1 years) with acute leukaemia (264/423, 62.4%) and the median absolute neutrophil count at bacteraemia onset was 0x10(9)/L. The unadjusted 14 day mortality rate was higher for patients with CRGNB compared with CSGNB [45.6% (47/103) versus 15% (48/320), respectively (P<0.001)]. Adjusting to baseline prognostic factors, infection characteristics and the propensity score retained a significant association between CRGNB and 14 day mortality (OR 5.14, 95% CI 2.32-11.38). Including only the first bacteraemic episode per patient, 1 year mortality was 74.7% (68/91) for patients with CRGNB versus 49.8% (119/239) for patients with CSGNB (P<0.001). Adjusting for risk factors associated with 1 year mortality, the HR for mortality with CRGNB was 1.48 (95% CI 1-2.2). CRGNB bacteraemia was associated with several risk factors for mortality, including inappropriate empirical antibiotic treatment and less effective definitive antibiotics. Conclusions: This study demonstrated a significant adjusted association between CRGNB and mortality up to 1 year among haemato-oncological patients receiving chemotherapy.