Monotherapy is associated with a lower risk of mortality in patients infected with carbapenem-resistant Enterobacteriaceae without sepsis

Background: To determine the mortality-related risk factors for carbapenem-resistant Enterobacteriaceae (CRE) infection in hospitalized patients and to compare the clinical efficacy of different antimicrobial regimens, mainly from the perspective of mortality. Methods: : Data were retrospectively collected from a 3,000-bed regional medical center with CRE infections between January 2021 and June 2022. The clinical characteristics, microbiological characteristics, and antimicrobial therapies of the patients with different outcomes were analyzed. Mortality-related risk factors were analyzed by the Cox proportional regression model for multivariate analysis. Results: : 120 patients were included. All patients received definitive therapy, and 65.0% (78/120) received active drug treatment. Among those receiving active drug treatment, 65.4% (51/78) received combination therapy, and 34.6% (27/78) received monotherapy. The all-cause mortality of CRE infection was 20.8% (25/120). Multivariate analysis showed that the length of hospital stay after CRE infection (hazard ratio [HR], 0.868; 95% confidence interval [CI], 0.806-0.936; P = 0.000), Sequential Organ Failure Assessment (SOFA) score (HR = 1.169; 95%CI, 1.066-1.281; P = 0.001), central venous catheter (HR = 3.858; 95%CI, 1.411-10.547; P = 0.009), age (HR = 1.035; 95%CI, 1.002-1.070; P = 0.036), and combination therapy (HR = 3.152; 95%CI, 1.205-8.245; P = 0.019) were independent mortality risk factors after CRE infection. Subgroup analysis of the non-sepsis group among 78 patients who received active drug treatment showed significantly lower mortality in monotherapy than in combination therapy (0% versus 22.2%, P = 0.034). Patients who received carbapenem-containing therapy had significantly higher mortality than those who received carbapenem-sparing therapy (31.3% versus 13.9%, P = 0.022). Conclusions: : Patients with a higher SOFA score, central venous catheter, shorter hospital stay after CRE infection, older age, and combination therapy had poor outcomes. Since patients with non-sepsis have a lower mortality rate from monotherapy, combination antibiotic treatment should not be routinely recommended to treat CRE infections.