Tracking bla_CTX-M transmission through transposable elements in uropathogenic and commensal E. coli

Aim: To investigate the nucleotide sequences associated with transposable elements carrying bla_CTX-M allelic variants as potential markers for the transmission of antimicrobial resistance genes between domestic animals, humans and the environment. Materials & methods: We conducted whole-genome sequencing and analyzed the nucleotide sequences of most abundant bla_CTX-M allelic variants (bla_CTX-M-27, bla_CTX-M-55, and bla_CTX-M-65) in commensal Escherichia coli (n = 20) from household members in Quito and uropathogenic E. coli (UPEC) (n = 149) isolated from nine clinics in Quito, Ecuador. Results: The Ecuadorian commensal E. coli and UPEC displayed identical nucleotide sequences surrounding the bla_CTX-M gene and the synteny was similar to those found in other parts of the world; however phylogenetic analysis indicated that the genetic environments in Ecuadorian isolates were unique. Conclusion: These findings suggest that the nucleotide sequences flanking the bla_CTX-M genes may be useful for resolving ARG transmission pathways, especially inter-regional analyses.