Objectives: The aim of this study was to determine the prevalence of antibiotic-resistant bacteria, especially extended-spectrum beta-lactamase (ESBL) producing Escherichia coli, in samples from healthy adults, foods, food animals, and the environment in selected areas of Thailand. Methods: Samples were collected from stool specimens from adult food factory and food animal farm workers, fresh and cooked foods sold at markets, rectal swabs of healthy pigs and chickens, fresh pork meat from slaughterhouses, water samples from canals as well as fish and shrimp farm ponds, and stagnant water sources on pig farms. Antibiotic susceptibility was determined using the disk diffusion or agar dilution methods. Extended-spectrum beta-lactamase production was assayed using a double disk diffusion method. Results: Among 544 healthy adult food factory workers, 75.5% were positive for ESBL producing E. coli, while 77.3% of E. coli isolated from 30 healthy animal farm workers were positive. Amongst healthy food animals, ESBL producing status among E. coli isolates were more commonly detected in pigs (76.7%) than broilers (40%). Extended-spectrum beta-lactamase producing E. coli seemed to be more prevalent in fresh meat samples than in fresh vegetables, in fresh foods than in cooked foods, and in water samples collected from the animal farms than those from canals and fish and shrimp ponds. Conclusions: Extended-spectrum beta-lactamase producing E. coli isolates are prevalent amongst healthy individuals, foods along the food production chain from farms to consumers, and in the environment in selected areas in Thailand.

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