# A Retrospective Analysis of Extended-Spectrum β-Lactamase (ESBL)-Producing Enterobacterales Bacteremia in Tertiary Care Hospitals in the United Arab Emirates

## TL;DR

This study analyzed bloodstream infections caused by antibiotic-resistant bacteria in UAE hospitals and found that carbapenems were effective and linked to better patient outcomes.

## Contribution

The study provides new insights into the epidemiology and treatment of ESBL-producing Enterobacterales bacteremia in UAE tertiary hospitals.

## Key findings

- 44.2% of Enterobacterales bloodstream infections were caused by ESBL-producing strains.
- Carbapenems were fully effective against ESBL strains and showed a trend toward lower mortality.
- Delayed appropriate therapy increased mortality risk nearly threefold.

## Abstract

Introduction

The global increase in extended-spectrum β-lactamase (ESBL)-producing Enterobacterales (ESBL-E) has significantly complicated the treatment of bloodstream infections (BSIs). This study aimed to assess the epidemiology, antimicrobial resistance patterns, sources of infection (including vascular catheter-related and organ-based infections progressing to sepsis), and clinical outcomes of ESBL-associated BSIs in patients treated at two tertiary care hospitals in the United Arab Emirates (UAE), with particular focus on the impact of empirical antibiotic selection.

Methods

We conducted a retrospective cohort study of 176 patients with Enterobacterales BSIs screened at Tawam Hospital and Sheikh Tahnoon Medical City (STMC) in the UAE between January 1, 2024, and January 1, 2025. All consecutive adult patients (≥18 years) with laboratory-confirmed monomicrobial Escherichia coli (E. coli) or Klebsiella pneumoniae (K. pneumoniae) bacteremia and complete clinical and microbiological data who met eligibility criteria were included in the final cohort (n=172). Exclusion criteria included patients with polymicrobial bacteremia, isolates from non-blood sources, pediatric patients (<18 years), incomplete records, or carbapenem-resistant isolates. Data collected included patient demographics, microbiological findings, antimicrobial regimens, and clinical outcomes.

Results

Of the 176 patients screened, 172 met the inclusion criteria (four patients with carbapenem-resistant isolates were excluded), and 76 (44.2%) had ESBL-producing isolates; E. coli (44 cases, 58.4%) and K. pneumoniae (32 cases, 42.6%) predominated. ESBL strains were highly resistant to ceftriaxone (86.8%) and ciprofloxacin (71.4%) yet completely susceptible to carbapenems. Empirical carbapenem therapy was associated with numerically lower 30-day mortality compared with piperacillin-tazobactam (14.3% vs. 31.3%, p=0.12), although this difference did not reach statistical significance. Delayed appropriate therapy (>48 hours) increased mortality risk (odds ratio (OR): 2.9, 95% confidence interval (CI): 1.5-5.6, indicating nearly threefold higher odds of death); predictors of ESBL production were prior cephalosporin use (OR: 3.1, p<0.001), ICU admission (OR: 2.7, p=0.002), recent hospitalization (OR: 2.3, p=0.001), and Charlson Comorbidity Index (CCI) >4 (OR: 1.8, p=0.05).

Conclusions

Nearly half of carbapenem-susceptible E. coli and Klebsiella BSIs in the two centers in the UAE were ESBL-producing. Carbapenems retained full activity and offered a clinically meaningful survival advantage in high-risk patients. These findings support early risk-based carbapenem use and highlight the importance of antimicrobial stewardship and rapid diagnostics.