Risk Factors for Carbapenem-resistant Gram-negative Bacteremia in Intensive Care Unit Patients

Purpose: Carbapenem-resistant (CR) Gram-negative pathogens have increased substantially. This study was performed to identify the risk factors for development of CR Gram-negative bacteremia (GNB) in intensive care unit (ICU) patients.

Methods: Prospective study; risk factors for development of CR-GNB were investigated using two groups of case patients: the first group consisted of patients who acquired carbapenem susceptible (CS) GNB and the second group included patients with CR-GNB. Both case groups were compared to a shared control group defined as patients without bacteremia, hospitalized in the ICU during the same period.

Results: Eighty-five patients with CR- and 84 patients with CS-GNB were compared to 630 control patients, without bacteremia. Presence of VAP (OR 7.59, 95 % CI 4.54-12.69, p < 0.001) and additional intravascular devices (OR 3.69, 95 % CI 2.20-6.20, p < 0.001) were independently associated with CR-GNB. Presence of VAP (OR 2.93, 95 % CI 1.74-4.93, p < 0.001), presence of additional intravascular devices (OR 2.10, 95 % CI 1.23-3.60, p = 0.007) and SOFA score on ICU admission (OR 1.11, 95 % CI 1.03-1.20, p = 0.006) were independently associated with CS-GNB. The duration of exposure to carbapenems (OR 1.079, 95 % CI 1.022-1.139, p = 0.006) and colistin (OR 1.113, 95 % CI 1.046-1.184, p = 0.001) were independent risk factors for acquisition of CR-GNB. When the source of bacteremia was other than VAP, previous administration of carbapenems was the only factor related with the development of CR-GNB (OR 1.086, 95 % CI 1.003-1.177, p = 0.042).

Conclusions: Among ICU patients, VAP development and the presence of additional intravascular devices were the major risk factors for CR-GNB. In the absence of VAP, prior use of carbapenems was the only factor independently related to carbapenem resistance.