Gram-Negative Bloodstream Infections in a Medical Intensive Care Unit: Epidemiology, Antibiotic Susceptibilities, and Risk Factors for in-Hospital Death

Abstract

Purpose: Gram-negative bloodstream infection (GNBI) poses a serious threat to critically ill patients. This retrospective study aimed to uncover drug resistance of pathogens and the GNBI effect on in-hospital death and distinguish death risk factors in a medical intensive care unit (ICU). Patients and Methods: A retrospective study of all GNBI patients in the medical ICU of the Third Xiangya Hospital over 9 nine years was conducted. Blood samples were performed by a BACTEC 9240 system, MALDI-TOF MS, Bruker and Vitek-2 system. Logistic regression was used for analyzing risk factors for death. Results: Seventy-five episodes of GNBI developed in 68 (1.4%) out of 4954 patients over a span of 9 years. The most frequently isolated bacterium was Klebsiella pneumoniae, with the lungs as the predominant source of GNBI. The resistance rate of Gram-negative bacteria to polymyxin B was 11.6% after excluding those intrinsically resistant non-fermentative bacteria. All Enterobacter spp. were susceptible to ceftazidime/avibactam. Thirty-three (48.5%) patients underwent inappropriate empirical antibiotic treatment and 48 (70.6%) patients died during the hospitalization. Multivariate logistic regression analysis identified that lymphocyte count at GNBI onset ≤0.5×109/L, invasive mechanical ventilation, and septic shock were related to in-hospital death. Body mass index ≥23 and appropriate empirical antibiotic use after GNBI were negatively associated with in-hospital death. Conclusion: GNBI was a frequent complication among patients in the medical ICU. This study underscored the presence of diverse factors that either heightened or attenuated the risk of in-hospital death.