Genetic Contexts of Plasmid- and Chromosome-Mediated bla CTX-M-32 in Escherichia coli from Pigs and Poultry in the Western Region of Cuba

Abstract

Twenty-six genetically diverse Escherichia coli isolated from poultry and pigs in Cuba and harboring the extended-spectrum-β-lactamase (ESBL) gene bla_CTX-M-32 were sequenced using short- and long-read technologies to identify and characterize the ESBL-containing genetic elements, and their transferability was determined by conjugation. The bla_CTX-M-32 gene was located on plasmids in 15 E. coli (4 from pigs, 11 from poultry), on the chromosome in five porcine and four poultry E. coli, and on both the chromosome and plasmids in two poultry E. coli strains. The bla_CTX-M-32 plasmids of incompatibility groups IncF (n = 6) and IncX (n = 3) were detected in strains from chickens and pigs, and those of IncN (n = 4) and IncH (n = 4) were only present in poultry E. coli. The plasmids were conjugative except for the IncX1 and one of the IncFII and IncFIA plasmids that had truncations in the tra and trh regions. ISEc9-ISKpn26-bla_CTX-M-32-wbuC was the most common ESBL-carrying genetic context in both plasmids and chromosomes, and two other structures (ISKpn26-bla_CTX-M-32-wbuC, IS26-bla_CTX-M-32-wbuC) were less frequent. This study provides new insights into the genetic backgrounds of bla_CTX-M-32 and its spread through plasmids between genetically different E. coli from different animals and geographically distant farms.