# Extended-spectrum β-lactamase (ESβL)-producing Escherichia coli in antibiotic-free and conventional chicken meat, Brazil

## TL;DR

This study found antibiotic-resistant E. coli in both antibiotic-free and conventional chicken meat in Brazil, highlighting the risk of spreading drug-resistant bacteria.

## Contribution

The study identifies specific E. coli strains and resistance genes in different chicken meat production systems in Brazil.

## Key findings

- Five cephalosporin-resistant E. coli strains were isolated from antibiotic-free chicken meat, including ESβL and pAmpC producers.
- Four resistant E. coli strains were found in conventional chicken meat, with some linked to global poultry and polluted environments.
- Resistance genes for heavy metals, disinfectants, and pesticides were identified, along with virulence potential in some strains.

## Abstract

Contamination of food by antimicrobial-resistant pathogens poses significant risk to consumers and environment, potentially leading to foodborne illnesses, silent colonization, and dissemination of antibiotic-resistant bacteria across geographic borders.

This study analyzed 32 retail meat samples (12 chicken, 10 beef, and 10 pork) from conventional (CN) and antibiotic-free (AF) production systems in Brazil, assessing WHO bacterial priority pathogens through whole genome sequencing and microbiological methods.

Five broad-spectrum cephalosporin-resistant Escherichia coli strains were isolated from AF chicken meat, including four extended-spectrum β-lactamase (ESβL) producers belonging to sequence types (STs) ST117, ST443, ST1559 and ST3258, and one pAmpC producer carrying the blaCMY-2 gene and belonging to ST57. On the other hand, four E. coli strains resistant to 3rd generation cephalosporins were identified in CN chicken meat, being three ESβL producers of ST38, ST2179 and ST2040, and one pAmpC producer belonging to ST350. Genes conferring resistance to hazardous heavy metals, disinfectants, and pesticides were identified, whereas virulent potential of E. coli ST350 and ST2040 was predicted. Noteworthy, E. coli ST38 was genomically related to lineages previously identified in poultry (North America) and polluted environments (Europe), supporting an intercontinental dissemination within a One Health framework.

Our findings reinforce the need for continuous surveillance of WHO critical priority pathogens in the chicken meat supply chain from different production systems.