Objective To analyze the characteristics and influencing factors of elderly hospitalized patients with carbapenem-resistant gram-negative bacillus (CRO) infection in the intensive care unit (ICU) of a gradeⅡ level A general hospital in Yangpu District of Shanghai, and to provide scientific basis for the prevention and control of hospital-acquired CRO infection in such hospitals.

Methods The clinical data of elderly ICU patients (age ≥60 years) from January 2019 to December 2023 were retrospectively collected. A total of 122 cases with hospital-acquired CRO infection were used as the case group, and a total of 68 cases with carbapenem-sensitive gram-negative (CSO) infection were used as the control group. The clinical characteristics of the two groups were analyzed, and univariate analysis and logistic regression analysis were performed for screening for possible influencing factors on hospital-acquired CRO infection.

Results The main pathogens of CRO infection were carbapenem-resistant Acinetobacter baumannii (CRAB) (53 cases, 43.44%) and carbapenem-resistant Klebsiella pneumoniae (CRKP) (46 cases, 37.70%), and 17 patients (13.93%) had more than two types of CRO infection. Among the CRO infection, the main sites were lower respiratory tract infection (58 cases, 47.54%), ventilator-associated pneumonia (21 cases, 17.21%), and catheter-associated urinary tract infections (16 cases, 13.11%). The incidence rate of poor prognosis was higher in the CRO infection group (54.10%) than that in the CSO infection group (36.76%) (P=0.021). The results of univariate analysis showed that male, history of hospitalization within three months, chronic respiratory disease, hypoproteinemia, anemia, and history of invasive procedures prior to infection, including indwelling central venous catheter, invasive mechanical ventilation, urinary catheter, gastric tube placement and parenteral nutrition, in addition, heparin anticoagulation, the use of broad-spectrum penicillin, third-generation cephalosporins, fluoroquinolones, carbapenems, carbapenems combined with fluoroquinolones, carbapenems combined with glycopeptides, use of ≥3 antibiotics and long time of antibiotic use prior to infection were all associated with the CRO infection (P<0.05). The results of logistic regression analysis showed that use of carbapenems (OR=7.739, 95%CI: 2.226‒26.911), ≥3 types of antibiotics (OR=6.307, 95%CI: 1.674‒23.754), invasive mechanical ventilation (OR=4.082, 95%CI: 1.795‒9.281), urinary catheter (OR=3.554, 95%CI: 1.074‒11.758), and comorbid hypoproteinemia (OR=4.741, 95%CI: 2.039‒11.022) and diabetes (OR=3.245, 95%CI: 1.344‒7.839) were positively correlated with the risk of CRO infection.

Conclusion Concurrent use of carbapenems with multiple other antibiotics, as well as the use of invasive mechanical ventilation, urinary catheter, and comorbid hypoproteinemia and diabetes, may be associated with an increased influencing of CRO infection. More attention should be paid to the prevention and control of infection in elderly patients with the above-mentioned risk factors, and active screening of drug-resistant bacteria should be strengthened. Besides, the rational use of broad-spectrum antibiotics such as carbapenems, avoiding unnecessary invasive operations, and paying attention to patient nutrition and blood glucose control all can reduce the incidence of CRO infection and help to improve clinical outcomes.