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

Abstract:

Aim: To investigate the nucleotide sequences associated with transposable elements carrying bla<inf>CTX-M</inf> 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<inf>CTX-M</inf> allelic variants (bla<inf>CTX-M-27</inf>, bla<inf>CTX-M-55</inf>, and bla<inf>CTX-M-65</inf>) 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<inf>CTX-M</inf> 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<inf>CTX-M</inf> genes may be useful for resolving ARG transmission pathways, especially inter-regional analyses.