Prevalence, antimicrobial resistance, and extended-spectrum β-lactamase gene profiles of Escherichia coli isolated from poultry eggshells in Can Tho City, Vietnam.

BACKGROUND AND AIM: The emergence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in food sources poses a growing threat to public health. Poultry eggs may act as vehicles for these resistant bacteria, facilitating their transmission through the food chain. This study aimed to determine the prevalence, antimicrobial resistance (AMR) patterns, and ESBL-encoding genes among E. coli isolates recovered from chicken, duck, and quail eggs sold in Can Tho City, Vietnam.

MATERIALS AND

METHODS

A total of 900 eggs (300 each from chicken, duck, and quail) were collected from local markets, retail stores, and supermarkets between June and December 2024. E. coli isolates were identified through biochemical tests and polymerase chain reaction (PCR) targeting the uidA gene. ESBL production was determined using the disk diffusion method, and the presence of bla CTX-M, bla TEM, bla NDM, and bla SHV genes was confirmed by PCR. Antimicrobial susceptibility was tested against 10 antibiotics representing eight classes following Clinical and Laboratory Standards Institute (2021) guidelines.

RESULTS

Out of 179 pooled samples positive for E. coli, 52 isolates (29.1%) were confirmed as ESBL producers. The highest prevalence was observed in chicken (32.4%) and duck (32.8%) eggs, while quail eggs showed a prevalence of 20%. ESBL-producing isolates most frequently carried bla CTX-M (65.4%) and bla TEM (44.2%) genes, whereas bla NDM was detected in 1.9% of isolates and bla SHV was absent. All isolates were multidrug-resistant, exhibiting resistance to 4-9 antibiotic classes. High resistance was observed to amoxicillin-clavulanate (69.2%), ceftriaxone (69.2%), tetracycline (75%), and trimethoprim-sulfamethoxazole (61.5%). No E. coli was detected in supermarket eggs, suggesting improved hygiene practices reduce contamination.

CONCLUSION

The detection of ESBL-producing and multidrug-resistant E. coli on poultry eggshells underscores a significant public health concern. The predominance of bla CTX-M and bla TEM genes highlights the risk of resistance gene dissemination through the egg supply chain. Enhanced surveillance, responsible antibiotic use, and strict hygiene control in small-scale poultry production systems are urgently needed to mitigate the spread of AMR under the One Health framework.