Toward Antibiotic Stewardship: Route of Antibiotic Administration Impacts the Microbiota and Resistance Gene Diversity in Swine Feces

Abstract

Sequencing of plasmid-enriched samples revealed multiple genetic contexts for the resistance genes detected and highlighted the potential role of small plasmids in the movement of antibiotic resistance genes. The findings are informative for disease management in food animals, but also manure management and antibiotic therapy in human medicine for improved antibiotic stewardship.

Manure as a Potential Hotspot for Antibiotic Resistance Dissemination by Horizontal Gene Transfer Events

“…Tetracyclines and sulfonamides are two classes of antibiotics often used in veterinary medicine due to their broad-spectrum activity, relatively low toxicity and low price [53,54]. After administration, most tetracyclines are excreted as active compounds through feces and urine, which are spread in the environment by manure fertilization practices [55,56]. These compounds have a high affinity for soil organic matter [57].…”

Antibiotic Resistance: From Pig to Meat

“…The quantity of these components is higher when the pigs are treated with antibiotics than when the pigs are not treated. As stated in Section 2.1, this increase is greater when the antibiotics are administered in feed than when they are administered by injection [25].…”

“…Holmer et al have argued that the increase in strains of E. coli resistant to florfenicol may be due to co-selection with another given antibiotic or when pigs are treated for respiratory infections. Another study demonstrated that using tetracycline in pigs prompted co-selection for resistance genes for aminoglycosides and tetracycline [25]. These studies illustrate the importance of taking a wider view of antibiotic resistance.…”

“…Alali et al showed a correlation between the amount of tetracycline in pigs' food and the level of isolates that were resistant to this antibiotic in fecal samples [32], but they found no similar correlation when the antibiotic is given by injection. Another recent study showed that orally administered tetracycline causes the gut microbiota to be more exposed to the antibiotic than by injection, and therefore promotes an increase in antibiotic resistance in the gut [25]. Conversely, the study done by Graesbøll et al indicated that no significant difference was found in the proportion of resistant coliforms in the feces of pigs between tetracycline administered orally or by injection [33].…”

“…As mentioned in Section 2.1, the antibiotic administration method was found to influence the impact of treatment on the gut microbiota. Feed-based administration has a greater impact on the ARG level in the gut microbiome and causes a greater shift in microbial population than intramuscular injection [25]. In-feed antibiotics increases the quantity of ARGs in the microbiome.…”