Assessment of the environmental transmission dynamics of Escherichia coli-producing ESBL in wet market broiler chickens: A high-burden food safety concern.

Background: Foodborne pathogens, particularly antibiotic-resistant strains, pose a significant threat to public health globally.

Objective: To explore the emergence and spread of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in the food chain, focusing on broiler chickens in wet markets.

Materials and methods: Specimens were inoculated into TBX medium supplemented with cefotaxime 4 ug/ml for selective isolation of ESBL-producing E. coli. Phenotypic and genotypic characterization of the isolates was performed, including species detection using PCR for E. coli identification with specific primers targeting the gene and a double diffusion synergy test for ESBL identification.

Results: A total of 262/305 (86%) samples were confirmed positive for ESBL-producing E. coli from broiler chickens and free-range chickens. bla _CTX-M were mostly identified among ESBL-producing E. coli from broiler chickens (91%) or free-range chicken (100%), followed by bla _TEM 20% and 23%, respectively. There were no identified bla _SHV genes. Among 50 ESBL producers, E. coli (31; 17.4% from broiler chickens and 19; 22.6% from free-range chicken) were identified with a co-incidence of bla _CTX-M and bla _TEM.

Conclusion: There is an increased prevalence of ESBL-producing E. coli in environmentally contaminated foods. Hygiene and antibiotic use regulations for poultry farms should be improved. ESBL genes among chickens are mainly bla _CTX-M (94%), followed by bla _TEM (21%), which has a lower incidence; no bla _SHV was detected.