# Risk factors, and outcomes of patients with carbapenem-resistant Enterobacterales bloodstream infection: an eight-year case-case-control study

## TL;DR

This study identifies risk factors for carbapenem-resistant Enterobacterales bloodstream infections and finds that prior antibiotic use and invasive procedures increase mortality risk.

## Contribution

The study introduces a case-case-control design to compare CRE-BSI with other infections and identifies specific risk factors and outcomes.

## Key findings

- Prior use of third-generation cephalosporins, carbapenems, quinolones, and glucocorticoids increases CRE-BSI risk.
- In-hospital mortality for CRE-BSI was 52.8%, with arterial catheter use linked to higher mortality.
- Respiratory and digestive system diseases were independent predictors of 30-day mortality in CRE-BSI patients.

## Abstract

Carbapenem-resistant Enterobacterales bloodstream infection (CRE-BSI) represents a major and urgent challenge to global public health. Some patients with CRE-BSI have a greater risk for poor clinical outcomes, thus identifying risk factors for CRE-BSI is required to determine the most at-risk populations. Here, we investigated risk factors for CRE-BSI by conducting a retrospective case-case-control study at Tianjin Medical University General Hospital, between 2017 and 2024. A total of 144 patients with CRE-BSI were enrolled in this case-case-control study. Each case was matched simultaneously to a patient with carbapenem-susceptible Enterobacterales BSI (CSE-BSI) and a control patient with non-Enterobacterales bacteremia in a 1:1:1 ratio. This design facilitated the analysis of risk factors and a comparison of 30-day survival outcomes among groups. Multivariable logistic regression identified distinct risk factor profiles for different infections. Surgical history emerged as an independent risk factor for Enterobacterales-BSI. Independent risk factors for CRE-BSI encompassed prior exposure to third-generation cephalosporins (OR = 1.94), carbapenems (OR = 3.45), quinolones (OR = 2.54), and glucocorticoids (OR = 2.55), in addition to a history of surgery (OR = 2.44) and gastric tube insertion (OR = 2.45). In-hospital mortality for CRE-BSI reached 52.8%. Furthermore, arterial catheter use (OR = 2.50) was identified as an independent risk factor for in-hospital mortality in patients with CRE-BSI. Cox proportional hazards modeling revealed several independent predicators of 30-day mortality: patient group (HR = 1.37; 95% CI, 1.01–1.86; p = 0.04), age ≥ 65 years (HR = 0.43; 95% CI, 0.20–0.93; p = 0.03), respiratory diseases (HR = 3.17; 95% CI, 1.54–6.51; p = 0.002), and digestive system diseases (HR = 1.79; 95% CI, 1.03–3.10; p = 0.04). Thus, a comprehensive evaluation of underlying diseases, antibiotic usage, and invasive procedures is required to reduce CRE-BSI-associated mortality. Given the notable morbidity and mortality, as well as constrained therapeutic options, associated with CRE-BSI, identifying risk factors for CRE-BSI is urgently required for effective disease prevention and to develop novel therapeutic strategies.