Clinical and molecular characteristics, risk factors and outcomes of Carbapenem-resistant bloodstream infections in the intensive care unit.

BACKGROUND

To analyze the clinical characteristics and outcomes of carbapenem-resistant (CRKp) and carbapenem-susceptible (CSKp) bloodstream infections (BSIs), and to study the risk factors for development of CRKp BSI and BSI-related mortality.

METHODS

A retrospective case control study of patients with BSI was conducted in the intensive care unit of the First Affiliated Hospital, Medical of College, Zhejiang University from January 2013 to December 2014. Carbapenem resistance was defined in accordance with the Clinical and Laboratory Standards Institute 2016 guidelines. Risk factors for the development of CRKp BSI and risk factors for mortality due to BSI were assessed. Virulence genes were detected by polymerase chain reaction assay.

RESULTS

In total, 48 patients were enrolled in the study, including 31 (65%) patients with CRKp BSI and 17 (35%) patients with CSKp BSI. CSKp infection was associated with more severe clinical symptoms, particularly a higher serum creatinine level (165.06 ± 127.01 in the CSKp group vs. 93.77 ± 84.35 μmol/L in the CRKp group,  0.039), but there was no significant difference in prognosis between the CSKp and CRKp groups. On multivariate analysis, indwelling central venous catheter ( 0.045) was the only factor independently associated with CRKp bacteremia. However, the mortality of BSI patients was not correlated with carbapenem resistance. In addition, the isolates had diverse clonality and different origins. The frequency of detection of the and virulence genes was higher in the CSKp group than in the CRKp group ( 0.04;  0.047).

CONCLUSIONS

Patients in the CSKp group experienced more severe clinical symptoms, although mortality did not differ significantly between the CRKp and CSKp groups. An indwelling central venous catheter was the only factor independently associated with CRKp BSI. The mortality of patients with BSI was not associated with carbapenem resistance. The frequency of virulence genes was higher in the CSKp group than in the CRKp group.