# Prevalence and Antimicrobial Resistance of Escherichia coli Isolated from Chicken Carcasses in Romania: Zoonotic Potential and Public Health Impact

## TL;DR

This study found that chicken carcasses in Romania are often contaminated with antibiotic-resistant E. coli, posing a public health risk.

## Contribution

The study provides new data on the prevalence and resistance patterns of E. coli in Romanian poultry, including ESBL-producing strains.

## Key findings

- E. coli was found in 36% of chicken carcasses and 64.6% of cecal samples.
- Multidrug resistance was observed in 34.3% of isolates, with high resistance to tetracycline, ampicillin, and trimethoprim–sulfamethoxazole.
- ESBL-producing E. coli was detected in 11.1% of carcass isolates and 11.8% of cecal isolates.

## Abstract

Poultry represents a substantial share of global food consumption, which places its microbiological safety among the key concerns in public health. Throughout slaughtering and subsequent processing stages, chicken carcasses may be exposed to bacterial contamination, particularly from microorganisms that inhabit the intestinal tract of animals, including Escherichia coli (E. coli). Some strains of this bacterium have developed resistance to antibiotics, meaning that infections caused by them may be more difficult to treat. In this study, chicken carcasses marketed in Romania together with cecal samples collected from slaughterhouses were examined to determine how frequently E. coli was present and whether the detected bacteria were resistant to commonly used antibiotics. The bacterium was found in 36.0% of the analyzed carcasses and 64.6% of cecal samples, and many isolates showed resistance to multiple antibiotics. These findings underscore a possible risk to consumers, as contaminated poultry carcasses may facilitate exposure to resistant microorganisms when adequate hygiene and biosecurity measures are not consistently ensured. The results underline the importance of responsible antibiotic use in animal production, effective hygiene measures during poultry processing, and proper food handling practices to reduce the risk of spreading antibiotic-resistant bacteria.

Antimicrobial-resistant bacteria associated with poultry production pose an ongoing challenge for food safety and veterinary public health. The present study evaluated the prevalence, antimicrobial resistance phenotypes, and selected resistance genes of E. coli recovered from broiler chicken carcasses and cecal content in Romania. Over a 12-month period in 2024, a total of 444 samples were collected, including 300 carcasses obtained from slaughterhouses and retail outlets and 144 cecal samples collected at slaughterhouses. Isolates were recovered using standard microbiological procedures and confirmed through biochemical and automated identification systems. Antimicrobial susceptibility was assessed using a minimum inhibitory concentration–based automated platform, and extended-spectrum β-lactamase (ESBL) production was evaluated phenotypically. Target resistance genes were investigated by PCR. E. coli was identified in 36.0% of carcass samples and 64.6% of cecal samples. High resistance rates were observed for tetracycline (82.6%), ampicillin (68.3%), and trimethoprim–sulfamethoxazole (61.2%), while multidrug resistance occurred in 34.3% of isolates. ESBL production was detected in 11.1% of carcass isolates and 11.8% of cecal isolates and was associated with the presence of blaCTX-M. Additional resistance determinants, including blaTEM, tetA, tetB, sul1, dfrA1, and aadA1, were widely distributed among isolates from both sources. The results suggest that poultry carcasses may contribute to the dissemination of resistant and ESBL-producing E. coli, reflecting intestinal carriage and contamination during processing. Strengthened antimicrobial stewardship, systematic resistance monitoring, and improved hygiene practices throughout the poultry production chain are essential to reduce the public health impact of resistant bacteria.