Microbiological Hazards of Animal-Based Foods in Brazilian Informal Markets: A case Study of Fishery and Meat Products in Northern Tocantins.

Abstract

The informal production and commercialization of animal-based foods remain widespread in regions distant from major urban centers in Brazil, often lacking sanitary inspections and posing significant public health risks. In this study, we aimed to evaluate the microbiological quality and safety of fish, shrimp, fresh pork sausages, and ground beef sold in street markets in the eastern Brazilian Amazon region. Representative samples were analyzed using microbiological and molecular methods. Quantitative assessments included mesophilic aerobes, psychrotrophs, and total and thermotolerant coliform counts. Qualitative analyses targeted Salmonella spp., Listeria monocytogenes, and diarrheagenic Escherichia coli (DEC). Most samples exceeded legal thresholds for microbial indicators, with psychrotrophs predominating and mesophilic aerobes reaching average abundances of 8.81 ± 0.35 log colony-forming units/g in some products. A total of 2092 single and multiplex PCRs were performed on 1,707 pathogen isolates. Overall, 77.5% of the samples tested positive for at least one pathogen: 62.5% for Salmonella spp., 27.5% for L. monocytogenes, and 12.5% for DEC. Notably, all the fish fillets were contaminated with Salmonella spp. Although shrimp samples had lower counts of indicator organisms, 70% tested positive for at least one pathogen. These findings demonstrate the widespread microbiological contamination and highlight the significant health risks posed by uninspected animal products in informal markets. These results underscore the urgent need for improved sanitary controls, consumer education, and stronger local enforcement to mitigate risks, reduce foodborne illnesses, and improve the safety of animal-derived foods in the Brazilian Amazon and other vulnerable regions.