Epidemiologic, clinical characteristics, and risk factors for adverse outcome in multiresistant gram-negative primary bacteremia of critically ill patients

Background: Characteristics and burden of primary bacteremia because of multidrug-resistant (MDR) gram-negative bacteria (GNB) in intensive care unit (ICU) patients remain understudied. Methods: A cohort study of patients with primary MDR GNB-related bacteremia from the ICU of a tertiary Greek hospital during a 3-year period was conducted for recognition of clinical characteristics and risk factors for adverse outcome. A case-control study was further performed to evaluate risk factors for development of MDR GNB-related primary bacteremia. Results: Fifty monomicrobial episodes of primary bacteremia because of Klebsiella pneumoniae (n = 20), Acinetobacter baumannii (n = 18), and Pseudomonas aeruginosa (n = 12) were recorded. The presence of diabetes mellitus was the only significant risk factor for development of MDR GNB-related primary bacteremia. Most episodes (78%) were ICU acquired in patients with prolonged mechanical ventilation and previous hospitalization in the ward. Mortality was 47.6% vs 19% of controls, P = .01. Mortality was higher in recurrent bacteremia (62.5%). Mortality was statistically associated with age (P = .002) and degree of multiorgan dysfunction expressed by sequential organ failure assessment score on day of bacteremia documentation (P = .001). Conclusion: Critically ill patients with MDR GNB-related primary bacteremia present significant mortality mainly associated with age and multiorgan failure. A baumanii bacteremia confers significant mortality compared with the benign course of K pneumoniae in such settings. Diabetes mellitus is a risk factor for development of such episodes, which may, in part, be general ward acquired, underlining the need for expanded vigilance.