Assessing the Effect of Oxytetracycline on the Selection of Resistant <i>Escherichia coli</i> in Treated and Untreated Broiler Chickens

• Main Authors: Ekaterina Pokrant (Author), María Belén Vargas (Author), María José Navarrete (Author), Karina Yévenes (Author), Lina Trincado (Author), Paula Cortés (Author), Aldo Maddaleno (Author), Lisette Lapierre (Author), Javiera Cornejo (Author)
• Format: Book
• Published: MDPI AG, 2023-11-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

Oxytetracycline (OTC) is administered in the poultry industry for the treatment of digestive and respiratory diseases. The use of OTC may contribute to the selection of resistant bacteria in the gastrointestinal tract of birds or in the environment. To determine the effect of OTC on the selection of resistant <i>Escherichia coli</i> strains post-treatment, bacteria were isolated from droppings and litter sampled from untreated and treated birds. Bacterial susceptibility to tetracyclines was determined by the Kirby-Bauer test. A total of 187 resistant isolates were analyzed for the presence of <i>tet</i>(A), (B), (C), (D), (E), and (M) genes by PCR. Fifty-four strains were analyzed by PFGE for subtyping. The proportion of tetracycline-resistant <i>E. coli</i> strains isolated was 42.88%. The susceptibility of the strains was treatment-dependent. A high clonal diversity was observed, with the <i>tet</i>(A) gene being the most prevalent, followed by <i>tet</i>(C). Even at therapeutic doses, there is selection pressure on resistant <i>E. coli</i> strains. The most prevalent resistance genes were <i>tet</i>(A) and <i>tet</i>(C), which could suggest that one of the main mechanisms of resistance of <i>E. coli</i> to tetracyclines is through active efflux pumps.

Item Description

10.3390/antibiotics12121652
2079-6382