Pork meat is in high demand worldwide and this is expected to increase. Pork is often raised in intensive conditions, which is conducive to the spread of infectious diseases. Vaccines, antibiotics, and other biosafety measures help mitigate the impact of infectious diseases. However, bacterial strains resistant to antibiotics are more and more frequently found in pig farms, animals, and the environment. It is now recognized that a holistic perspective is needed to sustainably fight antibiotic resistance, and that an integrated One Health approach is essential. With this in mind, this review tackles antibiotic resistance throughout the pork raising process, including their microbiome; many factors of their environment (agricultural workers, farms, rivers, etc.); and an overview of the impact of antibiotic resistance on pork meat, which is the end product available to consumers. Antibiotic resistance, while a natural process, is a public health concern. If we react, and act, collectively, it is expected to be, at least partially, reversible with judicious antibiotic usage and the development of innovative strategies and tools to foster animal health.

Antibiotic resistance is an issue in many areas of human activity. The mobilization of antibiotic resistance genes within the bacterial community makes it difficult to study and control the phenomenon. It is known that certain insertion sequences, which are mobile genetic elements, can participate in the mobilization of antibiotic resistance genes and in the expression of these genes. However, the magnitude of the contribution of insertion sequences to the mobility of antibiotic resistance genes remains understudied. In this study, the relationships between insertion sequences and antibiotic resistance genes present in the microbiome were investigated using two public datasets. The first made it possible to analyze the effects of different antibiotics in a controlled mouse model. The second dataset came from a study of the differences between conventional and organic-raised cattle. Although it was possible to find statistically significant correlations between the insertion sequences and antibiotic resistance genes in both datasets, several challenges remain to better understand the contribution of insertion sequences to the motility of antibiotic resistance genes. Obtaining more complete and less fragmented metagenomes with long-read sequencing technologies could make it possible to understand the mechanisms favoring horizontal transfers within the microbiome with greater precision.

Objectives: This project studied the impact of a chlortetracycline treatment in weaning piglets on the taxonomy and antibiotic resistance gene (ARG) content of the microbiomes on carcasses and loins. Methods: Two groups of piglets from two farrowing barns with either an average or a lower sanitary health status were used. Each group was divided in half: a control group and a treatment group receiving feed supplemented with 660 g of chlortetracycline per tonne for 21 days. The piglets then went through fattening and were sent to the abattoir when they reached the targeted slaughter weight. Results: The microbiomes of the pig carcasses and loins were sampled, and DNA was extracted and sequenced with a whole-genome approach. The microbiomes of the carcasses differed depending on the farrowing barn source in both taxonomical composition and ARG content; however, the microbiomes on the loins were similar, regardless of the farrowing barn source and the treatment group. Conclusions: While there were differences in the carcass microbiomes between treatments after processing by the abattoir, the loin microbiomes were consistent and unaffected by treatment with chlortetracycline or the sanitary status of the farrowing barn.